Do not rely on notifiction module being imported
This has worked so far mostly by accident, but it turned out to be
brittle while writing tests. This makes sure that the notification
module is always imported before use.
from query import *
from subqueries import *
from where import AND, OR
from datastructures import EmptyResultSet
__all__ = ['Query', 'AND', 'OR', 'EmptyResultSet']