private function _repack_utf7(string $str): string
    {
        return (string) \preg_replace_callback(
            '#\+([\\p{L}0-9]+)\-#ui',
            function ($matches) {
                return $this->_repack_utf7_callback($matches);
            },
            $str
        );
    }
private function _repack_utf7(string $str): string
    {
        return (string) \preg_replace_callback(
            '#\+([\\p{L}0-9]+)\-#ui',
            function ($matches) {
                return $this->_repack_utf7_callback($matches);
            },
            $str
        );
    }
private function _repack_utf7 ( string $ str ) : string { return ( string ) \ preg_replace_callback ( '#\+([\\p{L}0-9]+)\-#ui' , function ( $ matches ) { return $ this -> _repack_utf7_callback ( $ matches ) ; } , $ str ) ; }
UTF-7 decoding function.

@param string $str <p>HTML document for recode ASCII part of UTF-7 back to ASCII.</p>

@return string
UTF - 7 decoding function .