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 ldlq(bch):
    """creates the surface plots of a BCH reader object
    with a ld-lq identification"""
    beta = bch.ldq['beta']
    i1 = bch.ldq['i1']
    torque = bch.ldq['torque']
    ld = np.array(bch.ldq['ld'])
    lq = np.array(bch.ldq['lq'])
    psid = bch.ldq['psid']
    psiq = bch.ldq['psiq']

    rows = 3
    fig = plt.figure(figsize=(10, 4*rows))
    fig.suptitle('Ld-Lq Identification {}'.format(bch.filename), fontsize=16)
    fig.add_subplot(rows, 2, 1, projection='3d')
    i1beta_torque(i1, beta, torque)

    fig.add_subplot(rows, 2, 2, projection='3d')
    i1beta_psid(i1, beta, psid)

    fig.add_subplot(rows, 2, 3, projection='3d')
    i1beta_psiq(i1, beta, psiq)

    fig.add_subplot(rows, 2, 4, projection='3d')
    try:
        i1beta_psim(i1, beta, bch.ldq['psim'])
    except:
        i1beta_up(i1, beta, bch.ldq['up'])

    fig.add_subplot(rows, 2, 5, projection='3d')
    i1beta_ld(i1, beta, ld)

    fig.add_subplot(rows, 2, 6, projection='3d')
    i1beta_lq(i1, beta, lq)