The type signature of get_grouped_opcodes() was incorrect. Resulting in type errors when checking return values.
The usage of this function is like this:
groups = sm.get_grouped_opcodes() # groups is Iterable[List[Tuple[str, int, int, int, int]]]
for group in groups: # group is List[Tuple[str, int, int, int, int]]
for opcode in group: # opcode is Tuple[str, int, int, int, int]
Stephen Thorne