space between it and the parentheses, like this: ( * ).
*)
-(* Encoding of (+ 1 ( * (/ 6 n) 4)) *)
+(* Encoding of \n. (+ 1 ( * (/ 6 n) 4)) *)
let t1 = Branch ((Branch ((Leaf (Op2 (map2 (+)))),
(Leaf (Num (mid 1))))),
(Branch ((Branch ((Leaf (Op2 (map2 ( * ))),