Runs a Crank callback module as a supervised gen_statem process.

The Server calls the same handle/3 or handle_event/4 functions that Crank.crank/2 calls. It adds what pure functions can't do: execute timeouts, send replies, emit telemetry on every transition, and integrate with OTP supervision.

Two ways to use it

Separate logic and server modules:

defmodule MyApp.DoorServer do
  use Crank.Server, logic: MyApp.Door
end

{:ok, pid} = Crank.Server.start_link(MyApp.DoorServer, [])
Crank.Server.cast(pid, :unlock)

Inline -- the logic module is the server module:

defmodule MyApp.Door do
  use Crank
  use Crank.Server

  @impl Crank
  def init(_opts), do: {:ok, :locked, %{}}

  @impl Crank
  def handle_event(_, :unlock, :locked, data), do: {:next_state, :unlocked, data}
  def handle_event(_, :lock, :unlocked, data), do: {:next_state, :locked, data}
end

Both produce a supervised process. The callback module doesn't change.