def __init__(self, groups=None):
        super(GroupedRequirements, self).__init__(NamedRequirements)
        self.groups = groups or self.default_groups
        self.filename = None
        self.create_default_groups()
def __init__(self):
                self.stride = (4, 8, 16, 32, 64)
                self.short = (200, 100, 50, 25, 13)
                self.long = (334, 167, 84, 42, 21)