A Python module is an external class or set of functions that exist outside the main file of your program. This can be something that you built yourself, or it can be provided by the community.

Cython generates the second kind of module: C libraries that talk to Python’s internals, and that can be bundled with existing Python code. Cython code looks a lot like Python code, by design.

In Python, the mere act of making a function call incurs a relatively large amount of overhead. If some function is called repeatedly in a tight loop, even if it isn’t a long-running function ...