private function getIndentAt(Tokens $tokens, $index)
    {
        if (1 === Preg::match('/\R{1}([ \t]*)$/', $this->getIndentContentAt($tokens, $index), $matches)) {
            return $matches[1];
        }

        return null;
    }
private function getIndentAt(Tokens $tokens, $index)
    {
        if (1 === Preg::match('/\R{1}([ \t]*)$/', $this->getIndentContentAt($tokens, $index), $matches)) {
            return $matches[1];
        }

        return null;
    }
private function getIndentAt ( Tokens $ tokens , $ index ) { if ( 1 === Preg :: match ( '/\R{1}([ \t]*)$/' , $ this -> getIndentContentAt ( $ tokens , $ index ) , $ matches ) ) { return $ matches [ 1 ] ; } return null ; }
@param Tokens $tokens
@param int    $index  index of the indentation token

@return null|string
@param Tokens $tokens @param int $index index of the indentation token