def METHOD_NAME(self):
    """Add this plugin to the system plugin list."""
    global _LOADED_PLUGINS
    name = self.name
    if _LOADED_PLUGINS is None:
        _LOADED_PLUGINS = {}
    if name not in _LOADED_PLUGINS:
        _LOADED_PLUGINS[name] = self
    elif self.priority > _LOADED_PLUGINS[name].priority:
        _LOADED_PLUGINS[name] = self
        LOGGER.warning("System plugin %s replaced due to priority.", name)
    elif self.priority < _LOADED_PLUGINS[name].priority:
        LOGGER.warning("System plugin %s ignored due to priority.",
                       self.path)
    elif self.priority == _LOADED_PLUGINS[name].priority:
        raise SystemPluginError(
            "Two plugins for the same system plugin have "
            "the same priority: \n{} and \n{}."
            .format(_LOADED_PLUGINS[name], name))