public function getSignature(int $id): Signature
    {
        if (isset($this->signatures[$id])) {
            return $this->signatures[$id];
        }

        throw new \InvalidArgumentException('The signature does not exist.');
    }
public function getSignature(int $id): Signature
    {
        if (isset($this->signatures[$id])) {
            return $this->signatures[$id];
        }

        throw new \InvalidArgumentException('The signature does not exist.');
    }
public function getSignature ( int $ id ) : Signature { if ( isset ( $ this -> signatures [ $ id ] ) ) { return $ this -> signatures [ $ id ] ; } throw new \ InvalidArgumentException ( 'The signature does not exist.' ) ; }
Returns the signature at the given index.
Returns the signature at the given index .