code: function (testFn) {
          var me = this,
              old = me.getChildEls(),
              keepers = (me.childEls = []),
              n, i, cel;
  
          for (i = 0, n = old.length; i < n; ++i) {
              cel = old[i];
              if (!testFn(cel)) {
                  keepers.push(cel);
              }
          }
      }
docs: Removes items in the childEls array based on the return value of a supplied test
  function. The function is called with a entry in childEls and if the test function
  return true, that entry is removed. If false, that entry is kept.
  
  @param {Function} testFn The test function.