* FIX: Error in generate-code: BUG: unhandles single rv.

* Investigate what happens when an interrupt occurs during a write.

   > (define (f) (write (gensym)) (newline) (f))
   > (f)
   ...
   #{g17660 |adxhQB29QdSYPKBS|}
   #{g17661 |ZaFfTMGRz!c17&zm|}
   #{g17662 |>yF!AMbaIL$dTG>B|}#{g17662 |>yF!AMbaIL$dTG>B|}Error:
   interrupted.
   >

Two displays occurred at the end.