def to_division(division):
        """Serializes division to id string
        :param division: object to serialize
        :return: string id
        """
        from sevenbridges.models.division import Division
        if not division:
            raise SbgError('Division is required!')
        elif isinstance(division, Division):
            return division.id
        elif isinstance(division, six.string_types):
            return division
        else:
            raise SbgError('Invalid division parameter!')