private function callback(string $name)
    {
        if (!$this->hasCallback($name)) {
            throw new XslCallbackException('A callback with the name ' . $name . ' does not exist.');
        }

        return $this->callbacks[$name];
    }
private function callback(string $name)
    {
        if (!$this->hasCallback($name)) {
            throw new XslCallbackException('A callback with the name ' . $name . ' does not exist.');
        }

        return $this->callbacks[$name];
    }
private function callback ( string $ name ) { if ( ! $ this -> hasCallback ( $ name ) ) { throw new XslCallbackException ( 'A callback with the name ' . $ name . ' does not exist.' ) ; } return $ this -> callbacks [ $ name ] ; }
returns a callback

@param   string  $name
@return  object
@throws  \stubbles\xml\xsl\XslCallbackException
returns a callback