Result.Syntax
As described at https://ocaml.org/manual/latest/bindingops.html
val (let+) : ('a, 'e) t -> ('a -> 'b) -> ('b, 'e) t
val (and+) : ('a, 'e) t -> ('b, 'e) t -> ('a * 'b, 'e) t
val (let*) : ('a, 'e) t -> ('a -> ('b, 'e) t) -> ('b, 'e) t
val (and*) : ('a, 'e) t -> ('b, 'e) t -> ('a * 'b, 'e) t