073 effect branch multiple kinds

// Test: multiple distinct effect branches in a single event.
//
// The `tokenize` event yields TWO kinds: `! token` for each token found,
// `! warning` for each warning. The producer fires them in interleaved
// order. Consumer dispatches both kinds; each one lowers to a separate
// `fn` inside the synthesized Handlers struct. Proves the Handlers struct
// composes multiple handler-fns and that each call site routes to the
// right one. This is the pump-shape Lars mentioned for vaxis/Orisha:
// one event source emitting multiple kinds of signals, one consumer
// dispatching cleanly with type-safe exhaustiveness.

~import std/io

~pub event tokenize { source: []const u8 }
! token []const u8
! warning []const u8

~proc tokenize|zig {
    _ = source;
    token("first");
    warning("watch out");
    token("second");
    token("third");
    warning("almost done");
}

~tokenize(source: "ignored")
! token t |> std/io:print.blk {
    token: {{ t:s }}
}
! warning w |> std/io:print.blk {
    warning: {{ w:s }}
}