@type t() :: %XFsm.Machine{
  actions: %{required(atom()) => (... -> any())},
  actor: nil | pid(),
  always: [XFsm.Always.t()],
  context: XFsm.context(),
  events: [XFsm.Event.t()],
  guards: %{required(atom()) => (... -> any())},
  initial: atom(),
  state: nil | atom(),
  states: [XFsm.State.t()]
}