docs: function (a, element, event, callback) {
                  var cbCheck;
                  for (var i = 0, l = a.length; i < l; i = i + 1) {
                      var li = a[i];
                      if (li && this.typesUtil.isObject(li[FN]) && !li[FN].$Callback) {
                          cbCheck = ("fn" in callback) && (li[FN].fn == callback.fn);
                      } else {
                          cbCheck = (li[FN] == callback);
                      }
                      if (li && cbCheck && li[EL] == element && li[TYPE] == event) {
                          return i;
                      }
                  }
  
                  return -1;
              }