r""" Compare `a` and `b` (lists of strings); return a `Differ`-style delta. Optional keyword parameters `linejunk` and `charjunk` are for filter functions (or None): - linejunk: A function that should accept a single string argument, and return true iff the string is junk. T
(a, b, linejunk=None, charjunk=IS_CHARACTER_JUNK)