Re: python-mode (python.el): python-backspace

[Richard Stallman]

    If point is currently at column N, search backward for a line with
    indentation M < N.  Then delete characters to the left until column M
    is reached.

I suppose that could be useful in many modes.  Not, I think, in modes
that compute the exact indentation, such as Lisp mode and C mode.  But
there are many modes which don't have such careful
indentation computations.