> In fact, as I wrote above, lset-adjoin! doesn't make that much sense
> because the list argument cannot be mutated anyway because of how
> lset-adjoin! is spec'ed.

Does any implementation of SRFI 1 actually carry `lset-adjoin!`? I can't
find a single Scheme implementation that ships it, not even Guile or
scsh. If there are none, could we add a post-finalization note that says
the procedure is omitted?