splitting on 2 or more possible characters

[Skaperen]

this is easy enough to do, but IMHO, makes for some ugly code, compared to splitting on a single character (call split()). a string might have "foo-bar" or it might have "foo_bar". what i want to do is split it on either "-" or "_" so that i get ["foo","bar"] for both cases. there will never be a case of both "-" and "_" together in one string. but i might have more than 2 characters to split on. the splitter characters can be provided in whatever form works best (a list, or tuple, or set, or frozenset, or string). ideally, i'd like to do this in one line without making a function or class but i suspect making a function will be best.

then as the next split thing i'd like to split on a substring, such as "foo123bar" being by "123" to get ["foo","bar"]. i have put any thought into this, yet, but i'd guess there are many implementations of a wide spectrum of quality.