code: def TowerContext(tower_name, is_training, vs_name=''):
      
      if is_training:
          return TrainTowerContext(tower_name, vs_name=vs_name)
      else:
          return PredictTowerContext(tower_name, vs_name=vs_name)
docs: The context for a tower function, containing metadata about the current tower.
      Tensorpack trainers use :class:`TowerContext` to manage tower function.
      Many tensorpack layers have to be called under a :class:`TowerContext`.
  
      Example:
  
      .. code-block:: python
  
          with TowerContext('', is_training=True):
              # call a tensorpack layer or a tower function