protected function nextChar(string $str, int &$p): ?string
    {
        $p += strspn($str, " \t\r\n", $p);
        return isset($str[$p]) ? $str[$p] : null;
    }
protected function nextChar(string $str, int &$p): ?string
    {
        $p += strspn($str, " \t\r\n", $p);
        return isset($str[$p]) ? $str[$p] : null;
    }
protected function nextChar ( string $ str , int & $ p ) : ? string { $ p += strspn ( $ str , " \t\r\n" , $ p ) ; return isset ( $ str [ $ p ] ) ? $ str [ $ p ] : null ; }
Gets next non-whitespace character from input

@param string $str Input string
@param int    $p   Position within input string
@return string|null
Gets next non - whitespace character from input