'Serialize to a Mongo-storable format.'

def to_storable(self):

    return {'previous_version': self.previous_version, 'update_version': self.update_version, 'source_version': self.source_version, 'edited_on': self.edited_on, 'edited_by': self.edited_by, 'original_usage': self.original_usage, 'original_usage_version': self.original_usage_version}
