3 Checks for calls to `iter`, `iter_mut` or `into_iter` on collections containing a single item
7 It is simpler to use the once function from the standard library:
13 let b = Some(123).into_iter();
18 let a = iter::once(&123);
19 let b = iter::once(123);
24 The type of the resulting iterator might become incompatible with its usage