     spawn_link(fn -> begin_periodic_pinger(config) end)
     {:reply, :ok, config}
   end
+
+  # Implementation
 
   @doc """
   Pings peer_ids in random order serially.


  alias Vivaldi.Peer.{Connections, PingServer}

  def start_link(config) do
    node_id = config[:node_id]
    Logger.info "#{node_id} - starting PingClient..."
    GenServer.start_link(__MODULE__, config)
  end

  def handle_call(:begin_pings, _, config) do

        {:error, reason} ->
          Logger.error "#{node_id} - ping_multi to #{peer_id} failed. #{reason}"
      end
      :timer.sleep(config[:ping_gap_interval])
    end)
    begin_periodic_pinger(config)
  end
