f.py

    # class dict does internally what next example does explicitly (builds a dict of { cls.__name__ : cls }
    return f.map_keys(
        arg(last, call('lower')), # equivalent to next example lambda
        f.class_dict(
            common.service.RestartableService.__subclasses__(),
            common.service.Service.__subclasses__()
        )).get(service_name.lower())

    # list comprehension, but utilizing map_keys
    # map keys goes through an iterable and generates a dict
    # maybe my favorite one, but inefficient as it builds intermediate list and intermediate dict
    return map_keys(
        lambda v, k: v.__name__.lower(),
        [
            *common.service.RestartableService.__subclasses__(),
            *common.service.Service.__subclasses__()
        ]
    ).get(service_name.lower())


    # replaces map_keys with dict comprehension
    return {
        cls.__name__.lower(): cls
        for cls in [
            *common.service.RestartableService.__subclasses__(),
            *common.service.Service.__subclasses__()
        ]
    }.get(service_name.lower())


    # removed dict comprehension with on the fly matching and return (more efficient)
    service_name = service_name.lower()
    for cls in [*common.service.RestartableService.__subclasses__(),
                *common.service.Service.__subclasses__()]:
        if cls.__name__.lower() == service_name: return cls


    # even faster, not constructing intermediate list, but chaining iterables (itertools.chain)
    # --- went with this, this is pure python ---
    service_name = service_name.lower()
    for cls in chain(
            common.service.RestartableService.__subclasses__(),
            common.service.Service.__subclasses__()):
        if cls.__name__.lower() == service_name: return cls


    # fiterate is like chain() but will call functions encountered when neccessary during iteration
    # (we save on calls if we match early)
    service_name = service_name.lower()
    for cls in f.fiterate(
            common.service.RestartableService.__subclasses__,
            common.service.Service.__subclasses__):
        if cls.__name__.lower() == service_name: return cls

    # most efficient to write, no need to add __subclass__ to each element,
    # a bit harder to read but worth it for larger lists
    service_name = service_name.lower()
    for cls in f.fiterate(
            map(call('__subclasses__'),
                (common.service.RestartableService,
                 common.service.Service))):
        if cls.__name__.lower() == service_name: return cls