CheckTree

fun {CheckTree T1 T2}
   case T1
   of nil then T2 == nil
   [] tree(K1 V1 TL1 TR1) then
      case T2
      of nil then false
      [] tree(K2 V2 TL2 TR2) then
         K1 == K2 andthen
     V1 == V2 andthen
     {CheckTree TL1 TL2} andthen
     {CheckTree TR1 TR2}
      end
   end
end