What does the construction `if __name__ == '__main__'` do in a Python file?

The if __name__ == '__main__' construct in Python is used to determine whether the file is being run directly or imported as a module into another script.

When Python runs a file, it assigns the special variable __name__ the value '__main__'. If the file is imported, __name__ will be equal to the module's name.

This allows writing code that only executes when the file is run directly, such as tests or the program's entry point, and does not execute upon import.

Example:

def main():
    print("Program is running directly")

if __name__ == '__main__':
    main()