def METHOD_NAME(self, *args, **kwargs):
    """
    Generic query method.
    In reality, your storage class would have its own query methods,
    Performs a Mongo find on the Marketdata index metadata collection.
    See:
    http://api.mongodb.org/python/current/api/pymongo/collection.html
    """
    for x in self._collection.find(*args, **kwargs):
        x['stuff'] = pickle.loads(x['stuff'])
        del x['_id'] # Remove default unique '_id' field from doc 
        yield Stuff(**x)