This function is basically a shortcut of boot for accessors
        that have only the config dict argument.

        Args
        ----
          config (dict): the configuration dictionary

def register(cls, config={}):
        """
        This function is basically a shortcut of boot for accessors
        that have only the config dict argument.

        Args
        ----
          config (dict): the configuration dictionary
        """
        if cls.accessor is not None:
            if cls.instance is None:
                cls.instance = cls.accessor(config)