Function select_panic 

pub fn select_panic<T, M, R>(
    t: &T,
    rs: &mut dyn Iterator<Item = (&R, Update<T, M>)>,
) -> Option<Update<T, M>>
where
    T: Uniplate + Debug,
    R: Rule<T, M> + Debug,

Panics when called by the engine, printing the original subtree and all applicable rules and their results.

This is useful when you always expect no more than one rule to be applicable, as the engine will only call the selector function when there is an ambiguity in which to apply.

See the module-level documentation for more information.