import std;

​

void main(string[] args)

{

    alias lessTid = (in Tid a, in Tid b) => a.to!string < b.to!string;

    auto c = make!(RedBlackTree!(Tid, lessTid));

​

    c.insert(Tid.init);

    assert(c.length == 1);

​

    auto tid1 = spawn(() {});

    c.insert(tid1);

    assert(c.length == 2);

    auto tid2 = spawn(() {});

    c.insert(tid2);

    assert(c.length == 3, format!"3 is expected but %s"(c.length)); // Line 17

}

​