code: function(prop, value) {
  
        if ((prop === 'fill' || prop === 'overlayFill') && value && this.isSameColor()) {
          var i = this.paths.length;
          while (i--) {
            this.paths[i]._set(prop, value);
          }
        }
  
        return this.callSuper('_set', prop, value);
      }
docs: Sets certain property to a certain value
  @method _set
  @param {String} prop
  @param {Any} value
  @return {fabric.PathGroup} thisArg