Python 3 isinstance

[Lambert, David W (S&T)]

I have use case, needn't be dynamic, and it's not hard to enclose set as
tuple.  But I also write (for example)

__all__ = 'this that other'.split()
string_list = 'evenOneWord'.split()

instead of

__all__ = 'this','that','imTiredOfMistypingCommasAndQuotes'


if not isinstance(o,set_of_handled_types):
    raise TypeError('call blessed programmer, this cannot occur')
if isinstance(o,set_of_handle_types-treat_differently):
    treat_thusly(o)
elif isinstance(o,treat_differently):
    treat_differently(o)
elif etc.