Auto-generated `fn accepts_…(&self) -> bool` methods

[regexident]

Given a state-machine like traffic_light.rs, i.e. …

transitions!(Traffic,
  [
    (Green, Advance) => Orange,
    (Orange, Advance) => Red,
    (Red, Advance) => Green,
    (Green, PassCar) => [Green, Orange]
  ]
);

… it would be nice if machine would auto-generate helper methods on the outer enum type for checking input acceptance …

impl Traffic {
    pub fn accepts_advance(&self) -> bool {
        match self {
            Traffic::Green(_) => true,
            Traffic::Orange(_) => true,
            Traffic::Red(_) => true,
            _ => false,
        }
    }

    pub fn accepts_pass_car(&self) -> bool {
        match self {
            Traffic::Green(_) => true,
            _ => false,
        }
    }
}

… instead of requiring one to implement them manually, as shown in the example (fn can_pass(&self) -> bool).