out_of_protocol

    1..10
    |> Task.async_stream(fn x -> x*2 end, max_concurrency: 2, timeout: 7000, on_timeout: :kill_task)
    |> Enum.to_list()

    defmodule MyApp.User do
    ...
    def changeset(user, attrs) do
        user
        |> cast(attrs, [:email])
        |> validate_required([:email])
        # This matches the error from the DB uniq index to the :email field
        |> unique_constraint(:email)
    end