Django Stars

Please describe your company and your position there.

Position: Delivery Lead Company description: Online retail/e-commerce, Consumer electronics, Insurance, Travel, Mobile, Internet. Private label and Marketplace.

For what projects/services did your company hire Django Stars, and what were your goals?

Application development specialising in Django framework/python development. Ability to work autonomously within an agile framework and familiarity and experience using agile methodologies and tools English language speaking

How did you select this vendor and what were the deciding factors?

Vendor was selected based on particular skillset (Django framework) and experience working with similar sized companies within agile framework. Based on positive feedback reviews and competitive pricing, Django stars was selected.

Describe the scope of work in detail, including the project steps, key deliverables, and technologies used.

• Influencers project - development of Influencers functionality which allows users to earn money from affiliate links
• Product landing pages - development of special pages for product departments, categories, and collections with TOP-brands, TOP-products, and TOP-deals functionality
• Testfreaks Reviews Integration - integration with Testfreaks service which allows companies to extend product reviews from a huge real reviews database

How many people from the vendor's team worked with you, and what were their positions?

7-8 Full time employees: 1 x Project manager 2 x Front End engineers, 2-3x Back End engineers, 1x Quality Assurance

Can you share any measurable outcomes of the project or general feedback about the deliverables?

All are on track to meet key objectives Django Stars was instrumental in the successful delivery of these projects

Describe their project management style, including communication tools and timeliness.

Project management was excellent with constant communication on progress of deliverables. Being on a 7 hour time difference with Australia it was critical to maintain high level of communication flow. Django stars worked with Kogan at how we should continuously improve and better our communication both online and offline.

What did you find most impressive or unique about this company?

We appreciated their willingness to adapt their processes to not only align with our way of working but also to actively collaborate on improving practices, communication and alignment on delivery

Are there any areas for improvement or something they could have done differently?

Although manageable, splitting front-end and back-end development would sometimes create dependancies that needed to be managed carefully.

Please describe your company and your position there.

PADI® (Professional Association of Diving Instructors®) is the world’s largest ocean exploration and diver organization, operating in 186 countries and territories, with a global network of more than 6,600 dive centers and resorts and over 128,000 professional members worldwide. PADI enables people around the world to seek adventure and save the ocean through underwater education, life-changing experiences and travel I was originally the founder of Diviac, the startup that I sold to PADI in 2017. I am now PADI's Chief Product & Digital Officer.

For what projects/services did your company hire Django Stars, and what were your goals?

For my startup, Diviac, I initially hired Django Stars to build a web app for scuba divers to log their dives. From their, I had them build mobile apps for that same application. After 2 years and having built the most advanced logbook app to date, I had Django Stars build a full platform to power an Online Travel Agency business targeted at scuba divers.

The eco-system built included a B2C website, an internal reservation management system for our travel agents, a self-service extranet for our suppliers to manage their listing, a marketing portal for partners to take advantage of our affiliate program (home built) and a new mobile app for consumers to book scuba related activities (courses, dive trips, etc.)

How did you select this vendor and what were the deciding factors?

Django Stars came to me recommended but the decisive factors in choosing them was their size (I didn't want to work with just contractor or with a very large outsourcing company), their flexible approach and their partnership attitude (i.e. their desire to partner in building a successful solution and not just being developers)

Describe the scope of work in detail, including the project steps, key deliverables, and technologies used.

The scope is already described in the description of the challenge. Technologies used

• Python/Django - Django template
• Angular
• React
• React Native
• Next.js

How many people from the vendor's team worked with you, and what were their positions?

The Django Stars team size fluctuated over the years but we currently have a team of 7 with 2 Front End developers, 2 Back End developers, 2 QA and 1 Scrum Master.

Can you share any measurable outcomes of the project or general feedback about the deliverables?

The Diviac logbook has more than 75K users and remains one of the most advanced in the market. Diviac Travel that is now PADI Travel is the world's leading Online Travel Agency for Scuba Divers. The main testament of the great work done by Django Stars is the fact that a global leader like PADI acquired it. In addition, PADI has not only kept the Django Stars team after the acquisition, they have now declared it a strategic partner and has them involved in building software solutions outside of PADI Travel.

Describe their project management style, including communication tools and timeliness.

Flexible, constructive. Tools used include Email, Slack, Jira, Confluence and Google Meet. Communication channels are short. I have personally been talking or messaging with the team close to every day, even after the war in the Ukraine erupted.

What did you find most impressive or unique about this company?

The quality of their engineers and the work delivered. I liked the collaborative nature of our relationship.

Are there any areas for improvement or something they could have done differently?

Push back more when we shifted from the standard bi-weekly sprints to full Kanban during times of high stress with tight deadlines.

Please describe your company and your position there.

I am the CDO of Boa Lingua, a Swiss language travel provider focused on helping people to find language schools and courses as well as host families or residences right up to leisure activities all around the globe.

For what projects/services did your company hire Django Stars, and what were your goals?

We were looking for a development partner to build a bespoke solution from scratch. The goal was to replace an existing, outdated application landscape. Customers today expect an interactive platform that provides answers to all their questions about language travel. They are looking for inspiration, expert advice and real customer feedback. Our future application should be child's play to use and able to create dynamic shopping carts in real time. The new customized system needed to replicate the functionality of several older systems while leveraging newer technologies and a tailor-made setup to improve the customer experience and increase the efficiency of all processes along the customer journey.

How did you select this vendor and what were the deciding factors?

After months of research, Djangostars was the company that stood out. We assigned them a pre-development project phase to get an idea of how they work.

Describe the scope of work in detail, including the project steps, key deliverables, and technologies used.

Starting with our wireframes and business requirements, Djangostars turned our ideas into code. A powerful PIM and booking engine, our customized shopping experience with personalized offers and the advanced filter system are features we developed and implemented for the MVP. Upon completion, the MVP has been deployed and we continue to fine tune it as well as work on follow-on projects.

How many people from the vendor's team worked with you, and what were their positions?

The project team consisted of 7-8 people on the Djangostars side (backend + frontend developers, quality assurance engineers, project manager) and 4 project managers on our side. There was a fixed core team. Individuals, however, came and went depending on the project phase and the respective requirements.

Can you share any measurable outcomes of the project or general feedback about the deliverables?

Once the web application was completed our customers were able to utilize the benefits immediately. Our new website provides real time prices for thousands of dynamic packaged services. You find over 2.000 customer ratings and the best snapshots from our customers - All you need to make the right choice before venturing out into the world.

Describe their project management style, including communication tools and timeliness.

The project management was well organized! The whole team worked very well together.

What did you find most impressive or unique about this company?

From experience, I know the challenges and what makes development projects successful. The goal is to ensure quality, but also to be close to the business. Our own project managers were able to empower Djangostars' software developers to think in terms of products, not projects. This allowed them to give advice on how to use the best technologies and smart solutions. By working together as a team, we've achieved exceptional results.

Are there any areas for improvement or something they could have done differently?

So far everything is going smoothly. Provide them with a clear idea of how the software should work. Problems don't stop them. They find a solution to every challenge that arises in the course of developments.

Introduce your business and what you do there.

I’m the general manager of an IT service provider. We offer IT solutions across a range of industries. Our company also has a software development division where we produce products to support our IT work. 

What challenge were you trying to address with Django Stars?

We were developing a software product intended to support our general IT control reviews and our security reviews for customers. We’d begun developing the product and wanted to get it to the MVP stage quickly, so we hired Django Stars and their development team. 

What was the scope of their involvement?

The key deliverable was a government risk and compliance tool. We had planned 20 sprints to complete the MVP. Our team had already completed 10 sprints when our development members left the organization. Django started working on some of our modules at that point. They also managed the tasks and modules of the people they allocated to do the work.

What is the team composition?

We worked with five people from their team, including a backend developer, a frontend developer, a project manager, and a QA resource. It was essentially a full-stack development team. Our main point of contact was Iryna (Project Manager).

How did you come to work with Django Stars?

 We found it difficult to find Django developers in Australia, so I went to the internet and searched for such developers. I discovered that there seemed to be a decent supply of developers in Ukraine, and we heard good stories about them. I started searching for Django developers there, and Django Stars came up, along with other vendors. 

Django Stars appeared to be a lot more professional than other providers. On top of that, they were a little bigger than other teams; therefore, they were more capable of providing resources to us. Apart from that, other developers didn’t respond to us when we sent our requests. As a result, we hired Django Stars. 

How much have you invested with them?

We spent about $85,000 AUD (approximately $62,000 USD).

What is the status of this engagement?

The MVP development work lasted from August–November 2021. For context, we’re currently considering the requirements for the next development phase and introducing the software to the market. It’s quite likely that we’ll use Django Stars again in the future, but things can change. 

What evidence can you share that demonstrates the impact of the engagement? 

The MVP worked, and it was completed according to our requirements — this was our simplest measure of success. On top of that, Django Stars completed the product ahead of time; under our original schedule, we were supposed to finish the MVP in December 2021. Moreover, all of our Jira ticket backlogs were completed, and we were happy with the results the team delivered. 

How did Django Stars perform from a project management standpoint?

Django Stars were exceptionally professional. They were the best developers I’d worked with in terms of project management. The team was thorough, detailed, and clear in communication. Overall, they were highly responsive.

In terms of tools, we used Atlassian products such as Jira and Confluence. For communications, we used Slack and Zoom for meetings. 

What did you find most impressive about them?

The Django Stars team had high standards, which were obvious from the work they did. There was nothing more we could ask for; they were a professional organization that delivered what we asked them to deliver. We had a great experience in that regard. 

Are there any areas they could improve?

The only thing that was difficult for us was the time zone differences; we had to begin meetings in the evening because of the difference. However, this wasn’t Django Stars’ fault. 

Do you have any advice for potential customers?

The success of your development project all comes down to how thoroughly you prepare your requirements and how clearly you communicate them. 

For context, we had a clear set of requirements before going to the Django Stars team. We’d already created all Jira tickets and estimated their time requirements.  As a result, when Django Stars arrived, they had a clear picture of what we needed, and they were able to improve on our estimates and point out any issues they saw. This made our engagement work well.

Introduce your business and what you do there.

I’m the project manager of an entertainment company.

What challenge were you trying to address with Django Stars?

We hired Django Stars to create a web application.

What was the scope of their involvement?

Django Stars has built a website based on the Django framework and frontend. It’s a premium social media website where our users can create individual posts, content, or videos. Users can also subscribe and pay for a premium account.

What is the team composition?

I’ve worked with around eight people, but my main points of contact have been a project manager, relationship manager, and frontend developer. We also have backend developers, QA people, and a software architect.

How did you come to work with Django Stars?

We were looking for a company that could build a web app using the Django framework because it was very flexible for building new apps or websites. It was a good fit if we could have the whole payment system interacting with our social system. Django Stars came across as the friendliest and most helpful company to speak with.

How much have you invested with them?

We’ve spent around $150,000.

What is the status of this engagement?

We started working with Django Stars in August 2020. The project is ongoing.

What evidence can you share that demonstrates the impact of the engagement?

There have been a few mentions that we’ve wanted, and the first is the backend system. We need to ensure that the payment systems Django Stars put in place and the way they hook up our site function to accept payments. This is the most important factor and what distinguishes our website from others. Django Stars has executed the payment side flawlessly. 

The second aspect is the functionalities of the social site, such as how quickly comments are posted and how seamlessly photos and videos are uploaded because it needs to be seamless on a social media site. That has been very easy for Django Stars because they have experience doing that. Nobody had any issues with that relative performance at the moment.

Finally, we’re measuring the accuracy and functionality of the frontend design, which we’ve had issues with. This includes how the website looks and reacts to people using it. Unfortunately, in the final presentation a few weeks ago, the deliverables were a bit off and not quite accurate to what the stakeholders envisioned. 

How did Django Stars perform from a project management standpoint?

Django Stars has been good at meeting deadlines. They usually manage to hit deadlines 95% of the time. We’ve changed our plans halfway through the project, so it has been on Django Stars to still step up and complete that. 

The communication is exceptional. Django Stars always lets me know of any changes when something isn’t correct yet or why something will take longer than they originally envisioned.

What did you find most impressive about them?

Something positive about Django Stars’ is that they manage to pull off changes within the deadline. They’ve adapted to our changes.

Are there any areas they could improve?

I think the QA needs to be slightly better to ensure what needs to be seen in the final product. It’s a shame because there have been some things Django Stars has missed, which tarnished some of what they’ve done. 

Any advice for potential customers?

Be honest, transparent, and open to communication around what you’re expecting out of the project from the beginning. It has been a good way for us to go because we've started with a plan with Django Stars. Their team is very good at planning out projects and knowing what to do from the start.

Please describe your company and your position there.

I am Director of Product Management at a medical diagnostics company - we analyze the DNA in a blood sample to identify risk of diseases.

For what projects/services did your company hire Django Stars, and what were your goals?

We hired DjangoStars to build an external user facing web portal. This would be very helpful to our external users.

How did you select Django Stars and what were the deciding factors?

We are a small-ish company, about 60 people, born from Y-Combinator. Our main reasons for choosing DjangoStars was:

• they were really good at building Django applications, and our tech stack was Django-based.
• we loved the team we met, really good and professional.
• the size of the company and cultural values was a good match, we did not want to work with too large a company.

DjangoStars prioritizes close working relationships / collaboration.

Describe the scope of work in detail, including the project steps, key deliverables, and technologies used.

DjangoStars led the build out of this project end to end for us:

• They conducted interviews with our internal users
• They created user personas based on the interviews
• They created wireframes and detailed mocks/designs based on those wireframes.
• They fully managed the build out of the project, managing backend, frontend and any integrations.

The provided a lot of expertise on the right architecture and technology to use.

How many people from the vendor's team worked with you, and what were their positions?

6-8 people. 1 Tech lead 1 Backend Engineer 1 Frontend Engineer 1 Program Manager 1 UX designer 1 QA

Can you share any measurable outcomes of the project or general feedback about the deliverables?

The project was delivered on time and looked fantastic. We had been working closely together so we had come to know what to expect - DjangoStars is a solid team that can be relied upon to build a beautiful and robust tech solution to solve your problems. The are also extremely professional - the work is transparent, there is constant feedback and iterative improvements, and they will make sure you are satisfied with the solution they propose.

Describe their project management style, including communication tools and timelines.

Good initial planning to scope the project out and then break up the project into milestones. Very agile during execution - 2 week sprints that are preceded with sprint planning sessions and followed with sprint demoes. Constant feedback and looping to ensure the project is on track.

What did you find most impressive or unique about this company?

Super collaborative and close working relationship. Djangostars cares about their own employees a LOT, so the folks that work for you are a happy and motivated bunch.

Are there any areas for improvement or something they could have done differently?

Honestly, not much. I'll recommend DjangoStars highly any day.

Please describe your company and your position there.

I’ve been working as a Chief Product Officer on this project. The Straddle is a debt management mobile application with a focus on poker players. We have plans to go further and add poker game management features in the future.

Straddle debt manager - play easily with your money. Get full control under your private loans and debts. Track history, set deadlines, split debts among several users or into several transactions, and more.

For what projects/services did your company hire Django Stars?

We wanted to develop a mobile app from scratch based on our vision. Django Stars cooperated with us from the early stages and helped make this vision a reality.

What were your goals for this project?

We wanted to develop a cross-platform mobile app for personal finance and debt accounting. The applications enables people lend money and repay debts.

How did you select Django Stars?

I found the Django Stars website while I was searching for the best tech.stack for my financial app. After a short investigation, I got a feeling that we have a common understanding of how business and cooperation should be done.

After we discussed my project I asked them to share more information about the previous experience and references from their clients. I was satisfied with their approach to negotiation, pricing, and timelines, but the final decision was made after I checked video-reviews from their clients.

Describe the project in detail.

Django Stars provided a full turnkey solution for the mobile from start to production release and further support. This includes early ideation and UX/UI Design, Brand identity, development for iOS and Android, App backend, hosting etc.

What was the team composition?

The team of 10 specialists was allocated to this project, which has needed skill set to release a mobile app:

• Two Backend Engineers
• Three Frontend/React Native Engineers
• Two Quality Assurance Engineers
• UX/UI Designer
• Project Manager
• Business Analyst

Can you share any outcomes from the project that demonstrate progress or success?

We were looking for a real partner who can provide us not only with strong technical experience but also with domain expertise. The partner, who understands the business goals and is ready to deliver us a product in an accurate manner according to the agreed timeline and budget, right as Django Stars did.

They had started the project from the detailed business and processes investigation. After the usual workflow was defined, they transferred it to the desired flow and created a project architecture taking into account the possibility of future growth and updates implementation. They also had described possible risks and ways of mitigation for the most crucial of them.

The pre-development phase completed in tight cooperation with the Django Stars team proved their problem-solving skills, not just code writing. One of the most valuable points we’ve noticed is the full engagement of each team member in the project development process.

How effective was the workflow between your team and theirs?

Thanks to the Scrum methodology they used, we always knew the latest results and progress on the project. The planning process took place every two weeks, which gave us an understanding of what will be done in the next milestone. The team provided us with the reports after each sprint, together with the demo and retrospective.

The Jira, Confluence, and Slack were the main tools for planning, document processing, and communication. The overall management process is stable and predictable, which made us feel comfortable with long-term planning.

What did you find most impressive about this company?

As I mentioned before, the Django Stars team was fully engaged in the development process. They have been working together on each feature and constantly were providing us with their ideas regarding the project improvement and priorities on the project, which helped us to get a better version for the first release, i.e., we boosted our business thanks to such an approach from their side.

Their development process was clear and transparent. We got more than a team of developers. We got a real partner who cares about our success.

Are there any areas for improvement?

Their processes are well-established and the delivery procedure leaves behind all our expectations. I don’t think there is something they have to improve.

Introduce your business and what you do there.

I’m the IT director of a UV disinfection company. Our product is a robotic system consisting of three towers. Through tablets, users can disinfect rooms, primarily for healthcare environments to disinfect hospital rooms. Then, information is stored on that tablet and uploaded to a portal for reporting purposes. Hospitals can track bacteria and viruses in the hospital and if disinfection has been effective.

What challenge were you trying to address with Django Stars?

We had an old portal that wasn’t working very well. We realized it would be easier and cheaper to build a new platform rather than fix the old one. It was a difficult project because our previous developer didn’t document it that well, so Django Stars really had to start from scratch

What was the scope of their involvement?

Django Stars had to create all the same features but started from scratch. The original platform was written in .NET and C#, but we decided to move to Django and Python because it would make the codebase easier to maintain and more secure.

It’s a web-based portal and the tablet is connected to the portal through a web API. Everything is done on a TLS encrypted connection.  

What is the team composition?

I worked with a business liaison to get the project started. The team consisted of a project manager, 2–3 front end developers and user interface designer and back end developer, a senior backend developer, and an Android developer.

How did you come to work with Django Stars?

I went to the Django website and it featured a list of Django developers. I went through the entire list and earmarked the ones that looked suitable. I wanted a decent-size company that could meet our needs. I then researched their websites and contacted 3–4 different developers.

How much have you invested with them?

We spent $200,000–$999,999.

What is the status of this engagement?

The project lasted from April–September 2020.

What evidence can you share that demonstrates the impact of the engagement? 

The project itself is done, but we’re in a transition phase where we need our users to switch from the old to the new portal.

They delivered all the features we asked for. It did take them a little longer to deliver than expected, but that was because of issues we didn’t foresee in our older software.

Their testing was very thorough as well. They outlined how they conducted each test so I can replicate them in-house as well.

How did Django Stars perform from a project management standpoint?

Their project manager did an excellent job. We had sprint reviews on Google Meets every business day. Communication was excellent. Even though English wasn’t their first language, we never had a communication problem. Their English was very proficient.

They gave me access to Jira, so I could monitor their progress. I also used Slack for communication with the team.

What did you find most impressive about them?

They were clearly very knowledgeable. Everything is extremely well-organized. They’re very professional and easy to get along with. They make sure everything is done correctly and that the customer is very happy.

Are there any areas they could improve?

We had a bit of turnover with some probationary developers. It didn’t really affect their work, but that was the only thing that made me slightly uncomfortable.

Do you have any advice for potential customers?

You can help them by clearly defining what you want to achieve. That will also help them create a more accurate cost estimate.

Introduce your business and what you do there.

I’m the CEO and founder of Repositax, Inc. It’s based in San Diego, California. 

What challenge were you trying to address with Django Stars?

I asked them to help with an investment management platform for privately held companies that was initially focused on partnerships.

What was the scope of their involvement?

They helped build an application around an idea that I had. While they had a seedling of code to start with, they ended up building it from scratch in Python. 

They’ve done the database design, the backend development and design, and the frontend development and design. The application has launched. Now, we’re doing continuous improvement and new features.

What is the team composition?

My primary contact is one main project manager, we meet daily, and I talk with him 70% of the time. Secondarily I talk with the QA specialist 20% of the time. However, they don’t shield me from talking to backend developers directly.

How did you come to work with Django Stars?

I was looking for a company that wasn’t too big or too small. It needed to match my level of technical expertise to where I had the subject matter expertise. Also, I knew I wanted something developed in Python. 
 
I ended up interviewing over 15 different companies in various countries. I also considered hiring a local company or hiring freelancers. I looked at the companies’ websites and customer references. I also looked on Clutch reviews and made sure it was a reliable source. 

Eventually, I narrowed it down to three companies and interviewed them. Django Stars was number two on my final list. I initially chose a local company that had outsourced employees in a different country. That ended up not being a good fit, and I outgrew it quickly.

During that time, I kept in touch with Django Stars. They were very thoughtful and responsive, even though I hadn’t initially chosen them. Since we’d developed a good relationship, I decided to make a change and hire them after a year. 

How much have you invested with them?

We’ve invested $250,000 – $500,000.

What is the status of this engagement?

The billable hours for the project started in March, and we’re still working together today.

What evidence can you share that demonstrates the impact of the engagement? 

The application is finished, it works, and it has customers. I engage five vendors as my team, and Django Stars brings 80% of the hours and value out of all of my other vendors combined.

My CTO has been working in software development for over 30 years, and he's rated them very highly after working with them for a year. He’s worked in 16 countries on countless projects. Early in his career, he was a Python programmer.

How did Django Stars perform from a project management standpoint?

Django Stars is the lead vendor that helps coordinate the other vendors. The project manager helps me with priorities, he manages the team, and he’s a great sounding board. Every day, we talk for at least an hour. 

The owners of Django Stars have been great too. Every time I raise my hand, they’re ready to respond. I’m certainly not their biggest customer, but they don’t make me feel like a small one. I’ve been to Ukraine five times in the last 18 months.

What did you find most impressive about them?

I see the benefit of choosing a vendor that’s focused on Python. Their focus on Python is very apparent in their efficiency and interactions with me. There are no distractions, and they’re very focused on what I need. 

They’ve been in business for over 10 years, so they’re stable. They’ve been steadily growing since I met them. I’ve been to their offices and seen the culture of the company. They have a really good culture; the impression I had from their website and LinkedIn is exactly what their culture is like.

Are there any areas they could improve?

They have a ton of experience in the earlier stages of taking design concepts from a founder’s head and making it a reality. However, after the product has launched, different skillsets would be helpful. They’ve done a great job with me, and they’ve demonstrated great flexibility. However, it’s an area that they could improve on. When my CTO and I gave them some suggestions, they were very responsive, and they’ve adapted.

Do you have any advice for potential customers?

This applies to every outsourcing company on the planet. You should spend 30 to 90 days just doing planning, whiteboarding, and wireframing. It’ll save you three times the amount of money later on.

Specific to Django Stars, revaluate the team members you have after you go through the planning process. That will be key to your success once you start coding. 

Please describe your company and your position there.

We are a financial data distribution platform. We gather data from provider and resell it to clients. I'm am the CTO of Sanostro AG responsible for technology and product development.

For what projects/services did your company hire Django Stars?

We planned to develop a new analytics platform for our business. To automate all processes including advanced data combinations and simulations. We hired Django Stars to build the software for this platform.

What were your goals for this project?

To build a new platform from scratch.

How did you select this vendor?

We looked at different vendors in the region and had several meetings. In the end, we selected Django Stars because of the professional impression the gave.

Describe the project and the services they provided in detail.

Software development based on a scrum methodology with Backend, Frontend, Quality assurance and project management. With us, they developed mainly in Python and ReactJS.

What was the team composition?

2 Backend, 1 Frontend, 1 QA, 1 Project Manager

Can you share any information that demonstrates the impact that this project has had on your business?

The project was executed according to plan. We have been able to streamline our processes and reach more clients.

How was project management arranged and how effective was it?

The project management was good. Their initial estimates where upheld and we encountered no surprises.

What did you find most impressive about this company?

The ability to put together a good team in a short period of time impressed us. We had a some delays in our project start date and when we finally started they were able to find good people that could do the job very fast.

Are there any areas for improvement?

The work held very high quality but it took some time before the developers got used to the old systems that we integrated. But this is always the case when you work with 2 systems.