[ stack ]                   is parity (   --> s )

  [ 1 & ]                     is odd    ( n --> b )

  [ [] swap witheach
    [ nested
      i odd 2 * 1 -
      join nested join ] ]    is +signs ( [ --> [ )

  [ dup
    [ dup 0 = iff
        [ drop ' [ [ ] ] ]
        done
      dup temp put
      1 - recurse
      [] swap
      witheach
        [ i odd parity put
          temp share times
            [ temp share 1 -
              over
              parity share
              iff i else i^
              stuff
              nested rot join
              swap ]
          drop
          parity release ]
      temp release ]
    swap odd if reverse
    +signs ]                  is perms  ( n --> [ )

  3 perms witheach [ echo cr ]
  cr
  4 perms witheach [ echo cr ]