def __init__(self, name, host='127.0.0.1', port=27017):
        self.name = name
        self.host = host
        self.port = port
def __enter__(self):
        entering = not transaction_states[self.using]
        transaction_states[self.using].begin()
        self._no_monkey.__enter__(self)
        if entering:
            on_commit(transaction_states[self.using].commit, self.using)