Map namedtuples with json data.

def load_json(data=None, path=None, name='NT'):
    """ Map namedtuples with json data. """
    if data and not path:
        return mapper(json.loads(data), _nt_name=name)
    if path and not data:
        return mapper(json.load(path), _nt_name=name)
    if data and path:
        raise ValueError('expected one source and received two')