Redundant with `in` and removed from Python 3.
Removed odd, old and long-unused UpdatableDict (which defines and uses
has_key) and UpdatableStr (which was nearby and caught in the blast),
validated with al.
(lib2to3.fixes.fix_has_key)
* `<>` was removed and should be replaced by
`!=` (lib2to3.fixes.fix_ne)
* `\`` was removed and should be replaced by either `repr()` or the
`%r` format string modifier (lib2to3.fixes.fix_repr followed by
hand-rolled edition to replace concatenation)