'Resolve the named tuple constructor, aka the class\'s __call__ method.'

def resolve___call__(self, classty):

    instance_class = classty.instance_class
    pysig = utils.pysignature(instance_class)
    def typer(*args, **kws):
        try:
            bound = pysig.bind(*args, **kws)
        except TypeError as e:
            msg = ("In    '%s':    %s" % (instance_class, e))
            e.args = (msg,)
            raise
        assert (not bound.kwargs)
        return types.BaseTuple.from_types(bound.args, instance_class)
    typer.pysig = pysig
    return types.Function(make_callable_template(self.key, typer))
