public static function offset2key(array &$arr, $offset)
    {
        $keys = array_keys($arr);
        return isset($keys[$offset]) ? $keys[$offset] : false;
    }
public static function offset2key(array &$arr, $offset)
    {
        $keys = array_keys($arr);
        return isset($keys[$offset]) ? $keys[$offset] : false;
    }
public static function offset2key ( array & $ arr , $ offset ) { $ keys = array_keys ( $ arr ) ; return isset ( $ keys [ $ offset ] ) ? $ keys [ $ offset ] : false ; }
Returns the array key corresponding to a given array offset.
@param  Array  &$arr
@param  int $offset
@return string|int
Returns the array key corresponding to a given array offset .