code: function(key, value) {
        if (typeof key === 'object') {
          for (var prop in key) {
            this._set(prop, key[prop]);
          }
        }
        else {
          if (typeof value === 'function') {
            this._set(key, value(this.get(key)));
          }
          else {
            this._set(key, value);
          }
        }
        return this;
      }
docs: Sets property to a given value
  @method set
  @param {String} name
  @param {Object|Function} value
  @return {fabric.Group} thisArg
  @chainable