In the type state pattern you would have something like this

pub trait ValidState {}

struct StateMachine<'a, T>

where

  T: ValidState 

untyped: &'a mut UntypedStateMachine,

_marker: PhantomData<T>

}

fn reserve_right<'a>(state: StateMachine<'a, Begin>) -> StateMachine<'a, Reserved>

fn query<'a>(state: StateMachine<'a, Reserved>) -> StateMachine<'a, Queried>

fn record<'a>(state: StateMachine<'a, Queried>) -> StateMachine<'a, Recorded>