exp_domain.py

@classmethod
def create_default_exploration(
      cls, exploration_id, title=feconf.DEFAULT_EXPLORATION_TITLE,
      init_state_name=feconf.DEFAULT_INIT_STATE_NAME,
      category=feconf.DEFAULT_EXPLORATION_CATEGORY,
      objective=feconf.DEFAULT_EXPLORATION_OBJECTIVE,
      language_code=constants.DEFAULT_LANGUAGE_CODE):
      .
      .
      .
      .

      exploration = cls(
          exploration_id, title, category, objective, language_code, [], '',
          '', feconf.CURRENT_STATE_SCHEMA_VERSION,
          init_state_name, states_dict, {}, [], 0,
          feconf.DEFAULT_AUTO_TTS_ENABLED, False)

      exp_android_proto = cls.to_exploration_proto(
          cls, exploration_id, title, 0, init_state_name, exploration.states)
      exp_android_proto_size = int(exp_android_proto.ByteSize())
      cls.update_proto_size_in_bytes(cls, exp_android_proto_size)
      return exploration
      
def to_exploration_proto(
    self, exploration_id, title, version, init_state_name, states):
    """Calculate the exploration size by setting exploration proto.

    Args:
        exploration_id: str. The id of the exploration.
        title: str. The exploration title.
        version: int. The version of the exploration.
        init_state_name: str. The name of the initial state.

    Returns:
        exploration_proto: Exploration. The exploration
            proto object.
    """
    state_protos=self.to_state_proto(states)
    exploration_proto = exploration_pb2.Exploration(
        id=exploration_id,
        content_version=version,
        init_state_name=init_state_name,
        title=title,
        states=state_protos
    )
    print("------------------")
    print(exploration_proto)
    print("------------------")
    return exploration_proto
  

  def to_state_proto(self, states):
    state_protos = {}
    for (state_name, state) in states.items():
        state_proto = state_pb2.State(
            content=self.to_subtitled_html_proto(
                self, state.content
            ),
            recorded_voiceovers=self.to_recorded_voiceover_proto(
                self, state.recorded_voiceovers)
        )
        state_protos[state_name] = state_proto

    return state_protos

exp_services.py

# This method is already there is file
def apply_change_list(exploration_id, change_list):
  exploration = exp_fetchers.get_exploration_by_id(exploration_id)
  .
  .
  .
  exp_android_proto = exploration.to_exploration_proto(
      exploration_id, exploration.title, exploration.version,
      exploration.init_state_name, exploration.states)
  exp_android_proto_size = int(exp_android_proto.ByteSize())
  exploration.update_proto_size_in_bytes(exp_android_proto_size)
  return exploration