LowerCase and Underscore PHP array

underscore_array_keys

function underscore_array_keys($data){
	foreach ($data as $n => $v){
		$newKey = strtolower(preg_replace('/(?<=\\w)([A-Z])/', '_\\1', $n));
		unset($data[$n]);
		if (is_array($v)){
			  $data[$newKey] = underscore_array_keys($v);
		}else{
			$data[$newKey] = $v;
		}
  }
	return $data;
}


Converts:  Array( "User"=>array("id" => "123", "FirstName"=>"Mark"));
To:  Array( "user"=>array("id" => "123", "first_name"=>"Mark"));