[Python-3000] ABC method mismatch

[Raymond Hettinger]

[Fred Drake]
> I'd be happy seeing these methods added to tuple; there's
> no reason that they would only be useful on mutable sequences.

That reminds me, I've always thought Sequence.__contains__().
should always be accompanied by Sequence.index().  Their
use cases are strongly related:

  Good news: I searched your house and found your keys
  Bad news: I don't have method to tell you where I found them


Raymond