On Fri, Mar 20, 2020 at 11:56 AM Dennis Sweeney <sweeney.dennis650@gmail.com> wrote:

If ``s`` is one these objects, and ``s`` has ``pre`` as a prefix, then
``s.cutprefix(pre)`` returns a copy of ``s`` in which that prefix has
been removed. If ``s`` does not have ``pre`` as a prefix, an
unchanged copy of ``s`` is returned. In summary, ``s.cutprefix(pre)``
is roughly equivalent to ``s[len(pre):] if s.startswith(pre) else s``.

The second sentence above unambiguously states that cutprefix returns 'an unchanged copy', but the example contradicts that and shows that 'self' may be returned and not a copy. I think it should be reworded to explicitly allow the optimization of returning self.