嵌套和标签
外循环可以使用break或continue，当在处理嵌套循环时。在这种情况, 循环必须用一些被注解：&aposlabel, 标签必须被传递给%uA0break/continue语句.
%uA0
#![allow(unreachable_code)]
fn main() {
&aposouter: loop {
println!("Entered the outer loop")
&aposinner: loop {
println!("Entered the inner loop")
// This would break only the inner loop
//break
// This breaks the outer loop
break &aposouter
}
println!("This point will never be reached")
}
println!("Exited the outer loop")
}