The timer feature is certainly nice to have, but its hardcoded format of " ({}.{:02.0f})" is perhaps not the best choice in some cases. In my particular example, the tasks usually take minutes to hours, and the user doesn't care about fractions of a second.

I suggest modifying the timer argument to accept str | bool. The logic would look like this:

• False: no timer
• True: timer with the default formatting
• any s: str: timer with s as its format string,
  • s must have one or two slots, otherwise throw an exception.