nested depth 4

// Depth 4 test: start |> +1 |> +2 |> +3 |> +4 → result (10+1+2+3+4 = 20)
const std = @import("std");
~import std/io

~event add-one { value: i32 }
| done i32
~add-one => done value + 1

~event add-two { value: i32 }
| done i32
~add-two => done value + 2

~event add-three { value: i32 }
| done i32
~add-three => done value + 3

~event add-four { value: i32 }
| done i32
~add-four => done value + 4

~add-one(value: 10)
| done a |> add-two(value: a)
    | done b |> add-three(value: b)
        | done c |> add-four(value: c)
            | done d |> std/io:print.ln("{{d:d}}")