This is mostly harmless but I'm concerned that we're encouraging a new Python developer to:

* churn code in mostly minor ways, irrelevant to users

* altering code long known to be stable, increasing
  the risk of introducing new bugs or performance changes

* altering code in ways that are atypical for our 
  code base (i.e. the bool type isn't a norm in our
  code, we mostly use int for that)

* altering code without communicating with the developer
  who originally wrote that code (if they are still active)

* consuming the time of reviewers when they could be working
  on known bugs, legitimate feature requests, or documentation

* one-off or drive-by code alterations rather that what
  Guido calls "holistic refactoring" where we do clean-ups
  while understanding and thinking about the module as a
  whole and focusing on the user experience.

* unfortunately, making lots of random, minor changes to
  a code base in a major project is an addictive experience
  and IMO it would be best to re-channel it early, particularly
  if the changes are motivated by "I like my style of coding
  more than that of the original contributor".  Style changes
  are highly subjective and usually we defer to the original
  contributor who was closest to the problem being solved.