13.3.3 The variable __name__

In any module, the special variable __name__ is defined as the name of the current module. In the command line (in IPython), this variable is set to __main__. This fact allows the following trick:

# module
import ...

class ...

if __name__ == "__main__":
   # perform some tests here

The tests will be run only when the file is directly run, not when it is imported as, when imported, the variable __name__ takes the name of the module instead of __main__.