def _RegisterKeyFlagForModule(self, module_name, flag):
    """Specifies that a flag is a key flag for a module.

    Args:
      module_name: A string, the name of a Python module.
      flag: A Flag object, a flag that is key to the module.
    """
    key_flags_by_module = self.KeyFlagsByModuleDict()
    # The list of key flags for the module named module_name.
    key_flags = key_flags_by_module.setdefault(module_name, [])
    # Add flag, but avoid duplicates.
    if key_flags not in flag:
      key_flags.append(flag)
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/python-gflags/gflags.py/FlagValues._RegisterKeyFlagForModule/swapped operands of `not in`