cpp/ranges/join with view/iterator

The return type of, and of  when both the outer range  and the inner range  satisfy  and the parent  is a.

If either or  is not a simple view,  is true for iterators returned from the const overloads, and false otherwise. If and  are simple views,  is true if and only if  is a reference.

The name of this class template (shown here as ) is unspecified.