def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
def cumsum(X):
        """
        Y[i] = sum(X[:i])
        """
        (m,) = X.shape
        s_state = te.placeholder((m + 1,), dtype="int32", name="state")
        s_init = te.compute((1,), lambda _: tvm.tir.const(0, "int32"))
        s_update = te.compute((m + 1,), lambda l: s_state[l - 1] + X[l - 1])
        return tvm.te.scan(s_init, s_update, s_state, inputs=[X], name="cumsum")