handle_call_return() ::
  {:reply, term(), t()}
  | {:noreply, term()}
  | {:stop, term(), term()}
  | {:stop, term(), term(), t()}

handle_cast_return() :: {:noreply, t()} | {:stop, term(), t()}

handle_continue_return() :: {:noreply, t()} | {:stop, term(), t()}

handle_info_return() :: {:noreply, t()} | {:stop, term(), t()}

identity() :: {:event | :transition, Flexflow.key_normalize()}

result() :: {:ok, t()} | {:error, term()}

server_return() :: {:ok | :exist, pid()} | {:error, term()}

state()

t() :: %Flexflow.Process{
  __args__: Flexflow.process_args(),
  __context__: Flexflow.Context.t(),
  __counter__: integer(),
  __graphviz__: keyword(),
  __histories__: [Flexflow.History.t()],
  __identities__: [identity()],
  __loop_counter__: integer(),
  __opts__: keyword(),
  __tasks__: %{required(reference()) => term()},
  events: Flexflow.events(),
  id: Flexflow.id() | nil,
  module: module(),
  name: Flexflow.name() | nil,
  state: state(),
  transitions: Flexflow.transitions()
}