Where do normal people store function calls?

Question

Python

Hello.
There is an algorithm, each stage of which is written in different files. At the beginning of the first (main) stage, I called the functions related, in fact, to the first stage, at the end of the first file. And when the algorithm began to grow, I got new files, but I continued to call functions from these new files in the main, first file.
And where do normal people store function calls? Create a file with only function calls separately? Leave a similar, like mine, porridge? How are functions related to function calls of a particular file?

Answer 1

It's usually done like this:

1. Development of an application architecture diagram;
   
2. Decomposition of architecture to atomic operations;
   
3. A certain number of iterations of finalizing the architecture;
   
4. The breakdown of the system into systems / subsystems / modules / submodules and other levels - and this is where classes are formed, each of which includes a specific set of functions / procedures from a file or directory (module).