if __name__ == '__main__': in pyhton fulll explain code example

Example 1: python if __main__

#Add this code to run a support module on its own.
#Great for running quick tests.

if __name__ == "__main__":
	function_that_starts_the_module_to_run_on_its_own() 
    #or
    test_function_included_in_module()

Example 2: __name__== __main__ in python

# If the python interpreter is running that module (the source file)
# as the main program, it sets the special __name__ variable to have
# a value “__main__”. If this file is being imported from another 
# module, __name__ will be set to the module’s name.
if __name__=='__main__':
  # do something