public static function lower(string $str, string $encoding = null) : string
    {
        return mb_strtolower($str, $encoding ?: utils\Str::encoding($str));
    }
public static function lower(string $str, string $encoding = null) : string
    {
        return mb_strtolower($str, $encoding ?: utils\Str::encoding($str));
    }
public static function lower ( string $ str , string $ encoding = null ) : string { return mb_strtolower ( $ str , $ encoding ? : utils \ Str :: encoding ( $ str ) ) ; }
Converts all characters in the given string to lowercase.

@param   string      $str        The string to convert.
@param   string|null $encoding   The encoding to use.
@return  string                  The converted string.
Converts all characters in the given string to lowercase .