Unfortunately, it looks like there's no requirement for an abc.Sequence to implement the 3 argument form of seq.index, so I suppose this is technically just a documentation bug...

>>> range(5).index(2, 1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: index() takes exactly one argument (2 given)

>>> help(range.index)
Help on method_descriptor:

index(...)
    rangeobject.index(value, [start, [stop]]) -> integer -- return index of value.
    Raise ValueError if the value is not present.