Adds a match stage at the query
        :param query_dict: The params as dict
        :param query: The parameters of the query
        :return: The current object

def match(self, query_dict=None, **query):
        """
        Adds a match stage at the query
        :param query_dict: The params as dict
        :param query: The parameters of the query
        :return: The current object
        """
        if query_dict:
            self._q.append({'$match': query_dict})
        else:
            self._q.append({'$match': query})
        return self