How can a django project detect if the system has django installed?
Simply the module won't be found when you try to run your project.
You can run 'python' in your command line and try to 'import django' if it returns an error then django isn't found it means that django isn't installed on the current machine.
I've built a small project on my system.
After building the project, I put it on a USB drive, and copied to another system.
When I run the project, how can it detect if django is installed in the system or if the system has all of the the requirements for the project?
For example, I made a blog example project on a laptop, then copied that project(blog) onto a USB drive and then I copied that project(blog) to my own system. After copying, I tried to run the project. If django is installed then the project runs successfully. But when django is not installed it gives an error in the terminal. 
How can the program detect if the required (Django/Python) is installed or not?