Unlike iterators in many languages, which always have a distinct type such as Iterator<T>, an iterator in Go 1.23 is any function that accepts a yield func(T) bool. (The name "yield" is conventional but not required.) Often of course it has the type iter.Seq[T], but this isn't necessary, and when a method of a collection is itself an iterator (as opposed to returning one), as in this example:

func (c *Collection[T]) Elements(yield func(elem T) bool) { ... }

for range c.Elements { ... }

it may not be immediately obvious that one is looking at an iterator. Completion may be able to help here. Given a prefix for range c., we should offer completions such as for range c.Elements { ... }. Perhaps, in statement context, given the prefix c., it should offer not just c.Elements, but for for elem := range c.Elements { ... } (using the name of the yield parameter). There are likely other opportunities too.