Python __name__, __main__

test1.py
if __name__ == '__main__':
   print 'inside test1 main...'
else:
   print 'test1 imported: ' + __name__


test2.py
import test1

if __name__ == '__main__':
   print 'inside test2 main...'
else:
   print 'test2 imported: ' + __name__

test3.py
import test2

if __name__ == '__main__':
   print 'inside test3 main...'
else:
   print 'test3 imported: ' + __name__

python test1.py

Output:

inside test1 main...

python test2.py

Output:

test1 imported: test1

inside test2 main...

python test3.py    ##(from test1 -> test2 -> test3)

Output:

test1 imported: test1

test2 imported: test2

inside test3 main...