def get_pool(cls) -> Pool:
        """
        Yields:
            existing db connection pool
        """
        if len(cls._connection_params) < 5:
            raise ConnectionError('Please call SQLStore.connect before calling this method')
        if not cls._pool:
            cls._pool = yield from create_pool(**cls._connection_params)
        return cls._pool
Yields:
            existing db connection pool