All code needs to have an entry point.
For Python and some other languages, this is the start of the file.
For other languages, this is a special function name reserved for this purpose - generally, "main".
In the first kind of language, the thought process is basically: I have the flow of execution, starting at the top of the file. If I want to make a library, I should build the things I want to build, then get out of the way.
In the other kind of language, the thought process is basically: I am building a library. If I want to make an executable, I should create an entry point they the execution starts at.
The debate is honestly pretty dumb.
I always use
..and earlier in the code:
This helps to prevent people from arbitrarily running my code as a library or executable when I don't went them to.