Can you please give a more practical example of usage of name main?
__name__ __main__ usage
Special Variables
When the Python interpreter reads a source file, it first defines a few special variables. In this case, we care about the __name__ variable.
When Your Module Is the Main Program:
If you are running your module (the source file - foo.py) as the main program, e.g.
python foo.py
the interpreter will assign the hard-coded string __main__ to the __name__ variable, i.e.
__name__ = "__main__"
It’s as if the interpreter inserts this at the top of your module when run as the main program.
When Your Module Is Imported By Another
On the other hand, suppose some other module is the main program and it imports your module. This means there’s a statement like this in the main program, or in some other module the main program imports:
# Suppose this is in some other main program.
import foo
In this case, the interpreter will look at the filename of your module, foo.py, strip off the .py, and assign that string to your module’s name variable, i.e.
# It's as if the interpreter inserts this at the top
# of your module when it's imported from another module.
__name__ = "foo"