private function _getFieldsOutput(array $aFieldset, array $aFields, array $aCallbacks = array())
{
$_aOutput = array();
foreach ($aFields as $_isIndex => $_aField) {
$_aOutput[] = $this->_getEachFieldOutput($_aField, $_isIndex, $aCallbacks, $this->isLastElement($aFields, $_isIndex));
}
return implode(PHP_EOL, array_filter($_aOutput));
}