def METHOD_NAME(coding_system, tpp_concepts, raw_concepts):
    # search by a TPP concept code
    assert coding_system.search_by_code("22222") == {"22222"}
    # search by a raw code
    assert coding_system.search_by_code("44444") == {"44444"}
    # search by an unknown code
    assert coding_system.search_by_code("55555") == set()