/**
      * Returns the value of the selected radio button in the radio group, null if
      * none are selected, and false if the button group doesn't exist
      *
      * @param {radio Object} or {radio id} el
      * OR
      * @param {form Object} or {form id} el
      * @param {radio group name} radioGroup
      */ 
      function $RF(el, radioGroup) { 
          if($(el).type && $(el).type.toLowerCase() == 'radio') { 
              var radioGroup = $(el).name; 
              var el = $(el).form; 
          } else if ($(el).tagName.toLowerCase() != 'form') { 
              return false; 
          } 
       
          var checked = $(el).getInputs('radio', radioGroup).find( 
              function(re) {return re.checked;} 
          ); 
          return (checked) ? $F(checked) : null; 
      }