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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 peer_ips(peer_relation='cluster', addr_key='private-address'):
    '''Return a dict of peers and their private-address'''
    peers = {}
    for r_id in relation_ids(peer_relation):
        for unit in relation_list(r_id):
            peers[unit] = relation_get(addr_key, rid=r_id, unit=unit)
    return peers