Create a :py:class:`Node` instance.

        All args and kwargs are forwarded to the node.

        :returns: a :py:class:`Node` instance

def node(self):
        """Create a :py:class:`Node` instance.

        All args and kwargs are forwarded to the node.

        :returns: a :py:class:`Node` instance
        """

        if self.node_class is None:
            raise ValueError("You have to create an ``Item`` by calling ``__init__`` with ``node_class`` argument"
                             " or by decorating a ``Node`` class.")

        node = self.node_class(*self.node_args, **self.node_kwargs)
        node.__item__ = self

        return node