def getall(self):
        try:
            spec = {'data': {'$exists': 1}}
            fields = {'_id': 0}
            sort = [('tid', 1)]
            cur = self.db.docs.find(spec, fields, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        return [Document(**row) for row in cur]
def test_brewster_angle():
    m1 = Medium('m1', n=1)
    m2 = Medium('m2', n=1.33)
    assert ae(brewster_angle(m1, m2), 0.93, 2)
    m1 = Medium('m1', permittivity=e0, n=1)
    m2 = Medium('m2', permittivity=e0, n=1.33)
    assert ae(brewster_angle(m1, m2), 0.93, 2)
    assert ae(brewster_angle(1, 1.33), 0.93, 2)