def remove(self, elem):
        """Remove a requirement.

        :param elem: a string or :class:`Requirement` instance.
        """
        if isinstance(elem, text_type):
            for requirement in self:
                if requirement.package == elem:
                    return super(Requirements, self).remove(requirement)
        return super(Requirements, self).remove(elem)
def define_tables(cls, metadata):
        Table(
            "table1",
            metadata,
            Column(
                "id", Integer, primary_key=True, test_needs_autoincrement=True
            ),
            Column("data", String(30)),
        )
        Table(
            "table2",
            metadata,
            Column(
                "id", Integer, primary_key=True, test_needs_autoincrement=True
            ),
            Column("someid", None, ForeignKey("table1.id")),
        )