frenzy/lib/frenzy/pipeline/stage.ex

defmodule Frenzy.Pipeline.Stage do
  @callback apply(Map.t(), Map.t()) :: {:ok, Map.t()} | :tombstone | {:error, String.t()}

  @callback validate_opts(Map.t()) :: {:ok, Map.t()} | {:error, String.t()}

  @callback default_opts() :: Map.t()
end