`python-mode' are inappropriate for the derived mode; in particular, I'd
like to disable auto-guessing of the indentation by setting
`python-indent-guess-indent-offset' to nil. However,
`define-derived-mode' has no customization point for running code before
the parent mode function. What's the best way to solve this?
Add the code *after* running python-mode? After all, setting vars
before would be a waste since python-mode (like all other proper major
modes) begins by calling kill-all-local-variables (also known as
fundamental-mode).