code: function deleteProperty(target, key) {
            var deleted = target[key];
            delete target[key];
            instance.emit(GQLBase.EVENT_MODEL_PROP_DELETE, {
              model: target,
              key: key,
              deleted: deleted
            });
          }
docs: Proxy deleteProperty() handler. This is where the delete property
  events are fired from
  
  @method GQLBase~deleteProperty
  @param {Object} target the `GQLBase` model object
  @param {string} key the property name