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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def list_opts():
 """Returns a list of oslo_config options available in the library. The returned list includes all oslo_config options which may be registered at runtime by the library. Each element of the list is a tuple. The first element is the name of the group under which the list of elements in the second element will be registered. A group name of None corresponds to the [DEFAULT] group in config files. The purpose of this is to allow tools like the Oslo sample config file generator to discover the options exposed to users by this library. :returns: a list of (group_name, opts) tuples """

    from tvrenamer.common import tools
    all_opts = []
    all_opts.extend(tools.make_opt_list([CLI_OPTS,
                                         EPISODE_OPTS,
                                         FORMAT_OPTS], None))
    all_opts.extend(tools.make_opt_list([CACHE_OPTS], 'cache'))
    return all_opts