This always felt weird to me given that Python does a good job with dict:

    d = {}
    assert(d.get("blah"), None)

I was impressed by Rust the first time I run into:

    let mut last;
      for i in &[1, 2, 3] {
          last = i;
      }   
    println!("{}", last);

  >> borrow of possibly uninitialized variable: `last`