(VAR X Y Z)
(STRATEGY CONTEXTSENSITIVE 
  (first 1 2)
  (0)
  (nil)
  (s 1)
  (cons 1)
  (from 1)
)
(RULES 
first(0,X) -> nil
first(s(X),cons(Y,Z)) -> cons(Y,first(X,Z))
from(X) -> cons(X,from(s(X)))
)