code: def _initialize_tensor_name_to_ids(self):
      
      tensor_name_to_ids = {}
      for i, operation in enumerate(self._operations):
        for j, tensor in enumerate(operation.outputs):
          tensor_name_to_ids[tensor.name] = (i, j)
      return tensor_name_to_ids
docs: Initializer for _tensor_name_to_ids.
  
      Returns:
        a {string: (int, int)}, mapping the name of tensor T to the index of T's
            operation in _operations and T's index in T's operation's outputs.