FluentDOM\Serializer\Factory\Group::offsetSet PHP Method

    public function offsetSet($contentType, $factory)
    {
        $contentType = $this->normalizeContentType($contentType);
        if (!($factory instanceof SerializerFactory || is_callable($factory))) {
            throw new Exceptions\InvalidArgument('factory', 'FluentDOM\\Serializer\\Factory, callable');
        }
        $this->_factories[$contentType] = $factory;
    }