def _make_node(Name, Fields, Attributes, Bases):
    def create_node(self, *args, **kwargs):
        nbparam = len(args) + len(kwargs)
        assert nbparam in (0, len(Fields)), \
            "Bad argument number for {}: {}, expecting {}".\
            format(Name, nbparam, len(Fields))
        self._fields = Fields
        self._attributes = Attributes
        for argname, argval in zip(self._fields, args):
            setattr(self, argname, argval)
        for argname, argval in kwargs.items():
            assert argname in Fields, \
                    "Invalid Keyword argument for {}: {}".format(Name, argname)
            setattr(self, argname, argval)

    setattr(_sys.modules[__name__],
            Name,
            type(Name,
                 Bases,
                 {'__init__': create_node}))