trait PrintType {
    fn print_type(&self);
}

impl PrintType for char {
    fn print_type(&self) {
        println!("char");
    }
}

impl PrintType for f64 {
    fn print_type(&self) {
        println!("64-bit float");
    }
}

fn prints_type_of_args<T, U>(arg1: &T, arg2: &U)
    where T: PrintType,
          U: PrintType
{
    arg1.print_type();
    arg2.print_type();
}

fn main() {
    prints_type_of_args(&'a', &2.0);
    prints_type_of_args(&'a', &'b');
}