YamlMap map = ["a" : 1];
assert(map["a"] == 1);
map[1.YamlAlgebraic] = "a";
map["a"] = 3;
map["a"].get!long++;
map["a"].get!"integer" += 3;
map["a"].integer += 3;
assert(map["a"] == 10);
assert(map[1.YamlAlgebraic] == "a");

// foreach iteration
long sum;
foreach (ref key, ref value; map)
    if (key == "a")
        sum += value.get!long;
assert(sum == 10);