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 _visit_migrate_unique_constraint(self, *p, **k):
    """Drop the given unique constraint

    The corresponding original method of sqlalchemy-migrate just
    raises NotImplemented error

    """

    self.recreate_table(p[0].table, omit_uniques=[p[0].name])