A module can find out its own module name by looking at the predefined global variable __name__. If this has the value '__main__', the program is running as a script. Many modules that are usually used by importing them also provide a command-line interface or a self-test, and only execute this code after checking __name__:

def main():
    print 'Running test...'
    ...

if \_\_name\_\_ == '\_\_main\_\_':
    main()

CATEGORY: programming