def set_prefixes(sto):
    """Setter of ontology prefixes.
    Here all custom prefixes are specified.
    """

    sto.set_prefix('dbont', 'http://dbpedia.org/ontology/')
    sto.set_prefix('dbprop', 'http://dbpedia.org/property/')
    sto.set_prefix('nsprov', 'http://www.w3.org/ns/prov#')
    sto.set_prefix('vocvr', 'http://purl.org/voc/vrank#')
    sto.set_prefix('lingg', 'http://purl.org/linguistics/gold/')
    return sto