'Edges one hop out from Gx_node in the mapping should be
time-respecting with respect to each other, regardless of
direction.'

def test_one(self, pred_dates, succ_dates):

    time_respecting = True
    dates = (pred_dates + succ_dates)
    if any(((x is None) for x in dates)):
        raise ValueError('Date    or    datetime    not    supplied    for    at    least    one    edge.')
    dates.sort()
    if ((0 < len(dates)) and (not ((dates[(-1)] - dates[0]) <= self.delta))):
        time_respecting = False
    return time_respecting
