A skeleton code for Rust Iterator that does not consume items

task2.rs

pub struct TaskSetRefIterator<'a> 
{
  ....
}

impl<'a> Iterator for TaskSetRefIterator<'a> {
  type Item = &'a Task;
  
  fn next(&mut self) -> Option<&'a Task> {
    None
  }
}

impl<'a> IntoIterator for &'a TaskSet {
  type Item = &'a Task;
  type IntoIter = TaskSetRefIterator<'a>;
  
  fn into_iter(self) -> Self::IntoIter {
    TaskSetRefIterator { ... }
  }
}