What's the best practice for writing an "execute only" Python module?

I have a Python module that is intended exclusively for running as a script and never as something that should be imported, and I'd like to enforce (and communicate) that intention in my code.

What is the best practice for accomplishing this?

---

I can imagine a few options such as wrapping the whole file in

if __name__ == '__main__':
    # All the code in the module

or aborting at the start

if __name__ != '__main__':
    exit()

# All the code in the module

perhaps with a warning

if __name__ != '__main__':
    print('You should not import this')
    exit()

# All the code in the module

or even an assertion

assert __name__ == '__main__', 'You should not import this'

But I'm not sure which (if any) is appropriate, stylistically or technically.

Copyright Notice：Content Author:「orome」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/20923892/whats-the-best-practice-for-writing-an-execute-only-python-module