@classmethod
def get(cls, descriptors, config=None):
    """Get a connection from the registry based on the descriptor"""
    primary, secondary = descriptors
    if primary:
        cls.current = cls.connections.get(primary)
        if not cls.current:
            cls.currernt = cls._get_connection(primary, secondary, config)
        elif secondary:
            cls._replace_alias(cls.current, secondary)
    elif not cls.current:
        cls.current = cls._get_connection(config.uri, None, config)
    return cls.current
