fn foo(mut iter: impl Iterator
   i32>) {
    
   for i 
   in iter {
        
   // do something...
        
   if i 
   == 
   42 {
            
   // ughh
        }
    }
}
  

use for_each_repeat::{ForEachRepeat, LoopControl};

fn foo(mut iter: impl Iterator
   i32>) {
    
   let _: 
   Option
   <()
   > 
   = iter.
   for_each_repeat(
   |i
   | {
        
   // do something...
        
   if i 
   == 
   42 {
            
   // process it...
            
   return LoopControl
   ::
   Repeat(i);
        }
        LoopControl
   ::
   Continue(())
    });
}