code: function(visible, force) {
  			if (this._foldingRulerVisible === visible && !force) { return; }
  			if (!visible) {
  				var textActions = this.getTextActions();
  				if (textActions) {
  					textActions.expandAnnotations(true);
  				}
  			}
  			this._foldingRulerVisible = visible;
  			if (!this._foldingRuler) { return; }
  			var textView = this._textView;
  			if (!textView.getModel().getBaseModel) { return; }
  			if (visible) {
  				textView.addRuler(this._foldingRuler);
  			} else {
  				textView.removeRuler(this._foldingRuler);
  			}
  		}
docs: Sets whether the folding ruler is visible.
  
  @param {Boolean} visible <code>true</code> to show ruler, <code>false</code> otherwise