{def dec2bin
 {lambda {:dec}
  {if {= :dec 0}
   then 0
   else {if {< :dec 2}
   then 1
   else {dec2bin {floor {/ :dec 2}}}{% :dec 2} }}}}
-> dec2bin

{dec2bin 5}    -> 101
{dec2bin 5}    -> 110010
{dec2bin 9000} -> 10001100101000

{S.map dec2bin 5 50 9000}
-> 101 110010 10001100101000

{S.map {lambda {:i} {br}:i -> {dec2bin :i}} 5 50 9000}
->
5 -> 101
50 -> 110010
9000 -> 10001100101000