   @doc false
   def next(sequence_name, formatter) do
     Agent.get_and_update(__MODULE__, fn(sequences) ->
-      current_value = HashDict.get(sequences, sequence_name, 0)
-      new_sequences = HashDict.put(sequences, sequence_name, current_value + 1)
+      current_value = Map.get(sequences, sequence_name, 0)
+      new_sequences = Map.put(sequences, sequence_name, current_value + 1)
       {formatter.(current_value), new_sequences}
     end)
   end

     end
  """
  def reset do
    Agent.update(__MODULE__, fn(_) -> HashDict.new end)
  end

  @doc false

defmodule ExMachina.Sequence do
  def start_link do
    Agent.start_link(fn -> Map.new end, name: __MODULE__)
  end

  @doc """
