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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 rdfs_properties(rdf):
 """Perform RDFS subproperty inference. Add superproperties where subproperties have been used."""


    # find out the subproperty mappings
    superprops = {}  # key: property val: set([superprop1, superprop2..])
    for s, o in rdf.subject_objects(RDFS.subPropertyOf):
        superprops.setdefault(s, set())
        for sp in rdf.transitive_objects(s, RDFS.subPropertyOf):
            if sp != s:
                superprops[s].add(sp)

    # add the superproperty relationships
    for p, sps in superprops.items():
        logging.debug("setting superproperties: %s -> %s", p, str(sps))
        for s, o in rdf.subject_objects(p):
            for sp in sps:
                rdf.add((s, sp, o))