I feel like you would be better off separating functions from the data they
operate on here. In this case, you could represent the state of a stopwatch
with a map containing the start time and the time elapsed, and have
functions `stop`, `reset`, `start`, etc that take the stopwatch data
FWIW, I was not aware of `any?` when I read this thread, and I found its
semantics confusing -- I think `anything?` would be much clearer.
`anything?` also seems more obviously useful for defining specs (e.g. a
function can take _anything_ as an argument). It seems usual in Clojure for
scalar
