       defmodule Stack do
         use GenServer
 
-        def start_link(state) do
-          GenServer.start_link(__MODULE__, state, [name: :sup_stack])
+        def start_link(state, opts) do
+          GenServer.start_link(__MODULE__, state, opts)
         end
 
         def handle_call(:pop, _from, [h|t]) do

      supervisor specification to contain only one child. Many functions
      in this module behave slightly differently when this strategy is
      used.

  ## Name Registration


  Let's try it:

      GenServer.call(:sup_stack, :pop)
      ** (exit) exited in: GenServer.call(:sup_stack, :pop, 5000)

  Luckily, since the server is being supervised by a supervisor, the
  supervisor will automatically start a new one, with the default stack
