define... [rotate-two-bits lst
define.. [rotate-two-bits lst
or...
;; ROTATED
and..
[>= length.lst 2
append.. cdr.cdr.lst
 [list car.lst cadr.lst
;; UNCHANGED
and.. 
[< length.lst 2
lst
;; ERROR
[0
;;;;;;;;;;;;;;;;;;;;
or..
and....
=.. length.lst
length.rotate-two-bits.lst
=.. [apply + lst
[apply + rotate-two-bits.lst
null?.filter..
 lambda..(x)
  [and not.(= x 0) not.[= x 1
 lst
rotate-two-bits.lst
[0