setGetStartedButton(action) {
    const payload = (typeof action === 'string') ? action : 'BOOTBOT_GET_STARTED';
    if (typeof action === 'function') {
      this.on(`postback:${payload}`, action);
    }
    return this.sendProfileRequest({
      get_started: {
        payload
      }
    });
  }
React to a user starting a conversation with the bot by clicking the Get Started button.
Facebook docs: https://developers.facebook.com/docs/messenger-platform/reference/messenger-profile-api/get-started-button
@param {String|Function} action If action is a string, the Get Started button postback will be set to that string. If it's a function, that callback will be executed when a user clicks the Get Started button.