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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 ensureUniqueIDs(items):
 """ If action groups are repeated, then links in the table of contents will just go to the first of the repeats. This may not be desirable, particularly in the case of subcommands where the option groups have different members. This function updates the title IDs by adding _repeatX, where X is a number so that the links are then unique. """

    s = set()
    for item in items:
        for n in item.traverse(descend=True, siblings=True, ascend=False):
            if isinstance(n, nodes.section):
                ids = n['ids']
                for idx, id in enumerate(ids):
                    if id not in s:
                        s.add(id)
                    else:
                        i = 1
                        while "{}_repeat{}".format(id, i) in s:
                            i += 1
                        ids[idx] = "{}_repeat{}".format(id, i)
                        s.add(ids[idx])
                n['ids'] = ids