def all_peers(synset):
    """Get the set of all peers of the synset (including the synset).
       If the synset has multiple hypernyms then the peers will be hyponyms of
       multiple synsets."""
    hypernyms = synset.hypernyms()
    peers = []
    for hypernym in hypernyms:
        peers += hypernym.hyponyms()
    return set(peers)
