Emulate slicing for a method

[heras]

This works:

class Loc:
    def __getitem__(self, key):
        print(key.start, key.stop, key.step)

class DataFrame:
    def __init__(self, max_frame_length)
        self.max_frame_length = max_frame_length
        self.data = {}
        self.loc = Loc()

Thanks Ichabod!