Function solver 

pub fn solver<P>(
    puzzle: P,
) -> Result<Box<dyn Solve<PartOne = Box<dyn Display + Send + Sync>, PartTwo = Box<dyn Display + Send + Sync>>>, AocError>
where
    P: Puzzl<InputType = Arc<str>> + 'static,

Function to generate solver for a puzzle.

It returns Err(AocError) if no solver can be generated for the given puzzle’s year and day.