Base::filterFields

protected function filterFields(array $fields): array
{
	foreach (array_keys($fields) as $field)
	{
		if (mb_strpos($field, '~') === 0)
		{
			$fields[str_replace('~', '', $field)] = $fields[$field];
			unset($fields[$field]);
		}
	}

	return $fields;
}