matching multiple patterns at once in ocaml

Having a custom variant type as below:

type yolo = 
| A of string
| B of yolo
| C of yolo * yolo
| D of yolo * yolo

I also have a function that performs some operations on instances of yolo similar to this:

let rec swag y = 
  match y with
  | A _ -> 1
  | B _ -> 2
  | C (left,right) -> (swag left) + (swag right)
  | D (left,right) -> (swag left) + (swag right)

Since operations for cases C and D are exactly the same I would like to merge them, is it possible?

>Solution :

A pattern like pat1 | pat2 matches either of the two patterns:

let rec swag y = 
match y with
| A _ -> 1
| B _ -> 2
| C (left,right) | D (left,right) -> (swag left) + (swag right)

Naturally the two patterns must bind the same names (left and right in this case) with the same types.