it('works for arrays', function() {
   assert.deepEqual(
     rMap('toString', [42, 'A', true]),
     ['42', 'A', 'true'],
     'returns an array containing the results of the given method call applied to each member'
   );
 });

 this.getData = function() {
   return rMap('getData', items);
 };

    function getOptionTexts(labeledSelectField) {
      var optionElements = labeledSelectField.querySelectorAll('option');

      return rMap('textContent', optionElements);
    }

 this.getValue = function() {
   return rMap('getValue', valuableChildren);
 };