code: function _linkIdentity() {
      var identityOptions = {
              id: this.params.raw.user_id,
              accessToken: this.params.access_token,
              accessSecret: this.params.access_secret,
              screen_name: this.params.raw.screen_name
          };
  
      return BB.resolve(grasshopper.request(this.token).users.linkIdentity(this.user._id.toString(), 'twitter', identityOptions));
  }
docs: Utility function to link a user's twitter info to the current user.