code: function(sessionToken, options) {
        options = options || {};
  
        var user = Parse.Object._create("_User");
        return Parse._request({
          route: "users",
          className: "me",
          method: "GET",
          useMasterKey: options.useMasterKey,
          sessionToken: sessionToken
        }).then(function(resp, status, xhr) {
          var serverAttrs = user.parse(resp, status, xhr);
          user._finishFetch(serverAttrs);
          user._handleSaveResult(true);
          return user;
  
        })._thenRunCallbacks(options, user);
      }
docs: Logs in a user with a session token. On success, this saves the session
  to disk, so you can retrieve the currently logged in user using
  <code>current</code>.
  
  <p>Calls options.success or options.error on completion.</p>
  
  @param {String} sessionToken The sessionToken to log in with.
  @param {Object} options A Backbone-style options object.
  @return {Parse.Promise} A promise that is fulfilled with the user when
  the login completes.