def add(self, elem, replace=False):
        """Add a requirement.

        :param elem: a string or :class:`Requirement` instance.
        :param replace: if `True`, packages in the set with the same name will
            be removed first.
        """
        if isinstance(elem, text_type):
            elem = Requirement.coerce(elem)
        if replace and elem in self:
            self.remove(elem)
        super(Requirements, self).add(elem)
def __enter__(self):
        """
        Syntax sugar which helps in celery tasks, cron jobs, and other scripts

        Usage:
            with Tenant.objects.get(schema_name='test') as tenant:
                # run some code in tenant test
            # run some code in previous tenant (public probably)
        """
        connection = connections[get_tenant_database_alias()]
        self._previous_tenant.append(connection.tenant)
        self.activate()

        return self