d as {{"a", "b"}: {1, 2}} = {"a": 1}
dic = !d

dic.insert! "b", 2
assert dic.get("a") == 1
assert dic.get("b") == 2

dic.merge!({ "a": 1 })
x = dic.remove!("a")
assert x == 1

dics as Dict!({Str: [Int; _]}) = !{:}
dics.insert! "a", []
dics.insert! "b", [1, 2, 3]

Manager = Class {
    .tasks = List Dict! { Int: Str }
}
Manager.
    show_tasks! self, id: Int =
        for! self.tasks, task =>
            print! task[id]