draw chain + bitmap ->
  for chain x ->
    if x.code ->         
      - draw bitmap x                                                          ++- "draw ps x.figure.outline"
    else
      ...
    ;
  ;
_
  chain : symbol-chain
  bitmap : bitmap
;

draw -x = draw _(chain : symbol-chain) + _(bitmap : bitmap)                    ++- "draw  draw ..."