#version 100

import std.reo;

composite main(in a, out b) {
	channel c -> d;
	syncdrain(a, b);
}

// shadowing import
primitive syncdrain(in a, in b) {
	while (true) {
		sync {
			if (!fires(a) || !fires(b)) {
				block(a);
				block(b);
			}
		}
	}
}