src/Instruction/Relation/Relationship.php
protected function keyOr(string $property): string
    {
        return $this->key ? $this->key->find() : $property;
    }
protected function keyOr(string $property): string
    {
        return $this->key ? $this->key->find() : $property;
    }
protected function keyOr ( string $ property ) : string { return $ this -> key ? $ this -> key -> find ( ) : $ property ; }
Returns the key if one was provided, defaulting to the property name.

@param string $property The property name to use as fallback.
@return string          The key to use as offset for the input data.
Returns the key if one was provided defaulting to the property name .