Find the parent key of a value in a two-dimensional array

function find_keys_based_on_value($value, $array, $first_only = false, $key_names_only = false) {
	$results = array();
	foreach($array as $parent_key_name => $parent_key_values) {
		if(db::fast_is_array($parent_key_values)) {
			foreach($parent_key_values as $key_value) {
				if($key_value==$value) {
					if($first_only)
						return $key_names_only ? $parent_key_name : $parent_key_values; // return first key matched; exit function
					else
						$results[] = $key_names_only ? $parent_key_name : $parent_key_values; // keep result for output later
				}
			}
		}
	}
	return $results; // function will have stopped execution if $first_only = true, so it must be false
}