Return a workflow object from id.

def get(cls, id_):
        """Return a workflow object from id."""
        with db.session.no_autoflush:
            query = cls.dbmodel.query.filter_by(id=id_)
            try:
                model = query.one()
            except NoResultFound:
                raise WorkflowsMissingObject("No object for for id {0}".format(
                    id_
                ))
            return cls(model)