Figuring how to pass iterators for custom traits as function parameters

custom-iterators.rs

trait Blub {
  fn blub(&self) -> usize;
}

impl Blub for usize {
  fn blub(&self) -> usize {
    *self
  }
}

fn some_fn<'a, I: Iterator<Item = &'a usize>>(iterator: I) {
  for (idx, el) in iterator.enumerate() {
    println!("{}: {}", idx, el);
  }
}

fn some_fn2<'a, B: 'a + Blub, I: Iterator<Item = &'a B>>(iterator: I) {
  for (idx, el) in iterator.enumerate() {
    println!("{}: {}", idx, el.blub());
  }
}

fn main() {
  println!("Hello, world!");
  let v: Vec<usize> = (0..3).collect();
  let a = [7, 7, 8];
  println!("func1");
  some_fn(v.iter());
  some_fn(a.iter());
  some_fn(v[..].iter());
  some_fn(a[..].iter());
  println!("func2");
  some_fn2(v.iter());
  some_fn2(a.iter());
  some_fn2(v[..].iter());
  some_fn2(a[..].iter());
}