def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
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