def METHOD_NAME(plugin_name):
    '''
    Return a service (ie an instance of a plugin class).
    :param plugin_name: the name of a plugin entry point
    :type plugin_name: string
    :return: the service object
    '''
    if isinstance(plugin_name, string_types):
        for group in GROUPS:
            iterator = iter_entry_points(
                group=group,
                name=plugin_name
            )
            plugin = next(iterator, None)
            if plugin:
                return plugin.load()(name=plugin_name)
        raise PluginNotFoundException(plugin_name)
    else:
        raise TypeError('Expected a plugin name', plugin_name)