delete attachments from a volume

def delete_attachments(self, volumeID, attachmentsID):
        ''' delete attachments from a volume '''
        log.debug("deleting attachments from volume '{}': {}".format(volumeID, attachmentsID))
        rawVolume = self._req_raw_volume(volumeID)
        insID = [a['id'] for a in rawVolume['_source']['_attachments']]
        # check that all requested file are present
        for id in attachmentsID:
            if id not in insID:
                raise NotFoundException("could not found attachment '{}' of the volume '{}'".format(id, volumeID))
        for index, id in enumerate(attachmentsID):
            rawVolume['_source']['_attachments'].pop(insID.index(id))
        self._db.modify_book(volumeID, rawVolume['_source'], version=rawVolume['_version'])