code: function (config) {
  			var _config = objectAssign({}, { wait: true }, config);
  			this.navigate();
  			if (_config.wait) this.waitForSigninScreen();
  			return this;
  		}
docs: Navigates to the signin screen.
  
  @param {Object} config The config spec.
  @param {boolean} config.wait Whether to wait for the target UI.  Optional, defaults to true.