docs: function (prop, callback) {
              if (Crafty.support.setter) {
                  this.__defineSetter__(prop, callback);
              } else if (Crafty.support.defineProperty) {
                  Object.defineProperty(this, prop, {
                      set: callback,
                      configurable: true
                  });
              } else {
                  noSetter.push({
                      prop: prop,
                      obj: this,
                      fn: callback
                  });
              }
              return this;
          }