(VAR L N X )
(STRATEGY CONTEXTSENSITIVE
        (zeros ) 
        (cons 1) 
        (0 ) 
        (and 1) 
        (tt ) 
        (length 1) 
        (nil ) 
        (s 1) 
)
(RULES 
        zeros -> cons(0, zeros)
        and(tt, X) -> X
        length(nil) -> 0
        length(cons(N, L)) -> s(length(L))
        
)