code: function (array, begin, end) {
                  // After tested for IE 6, the one below is of the best performance
                  // see http://jsperf.com/slice-fix
                  if (typeof begin === 'undefined') {
                      return slice.call(array);
                  }
                  if (typeof end === 'undefined') {
                      return slice.call(array, begin);
                  }
                  return slice.call(array, begin, end);
              }
docs: at least IE6 uses arguments.length for variadic signature