defmodule MyStack do
  use GenServer

  def start_link(args) do
    GenServer.start_link(__MODULE__, nil, name: args[:name])
  end

  def init(_) do
    {:ok, []}
  end

  def handle_info({:push, el}, state) do
    {:noreply, [el] ++ state}
  end

  def handle_call(:pop, _from, [head | tail]) do
    {:reply, head, tail}
  end
end