code: def _get_main_module_defective_python_3x(self, fullname):
          
          if fullname != '__main__':
              return None
  
          mod = sys.modules.get(fullname)
          if not mod:
              return None
  
          path = getattr(mod, '__file__', None)
          if not (os.path.exists(path) and self._looks_like_script(path)):
              return None
  
          fp = open(path, 'rb')
          try:
              source = fp.read()
          finally:
              fp.close()
  
          return path, source, False
docs: Recent versions of Python 3.x introduced an incomplete notion of
          importer specs, and in doing so created permanent asymmetry in the
          :mod:`pkgutil` interface handling for the `__main__` module. Therefore
          we must handle `__main__` specially.