Specializations of elements_of encapsulate a range and
act as a tag in overload sets to disambiguate
when a range should be treated as a sequence
rather than a single value.
[Example 1: template<bool YieldElements>
generator<any> f(ranges::input_rangeauto&& r){ifconstexpr(YieldElements)co_yield ranges::elements_of(r); // yield each element of relseco_yield r; // yield r as a single value} — end example]