88     _LIBCPP_NO_UNIQUE_ADDRESS _Iter __begin_ = _Iter();  variable
99       : __begin_(std::move(__iter)), __end_(std::move(__sent))  in subrange()
106       : __begin_(std::move(__iter)), __end_(std::move(__sent)), __size_(__n)  in subrange()
109         _LIBCPP_ASSERT((__end_ - __begin_) == static_cast<iter_difference_t<_Iter>>(__n),  in subrange()
146       return _Pair(__begin_, __end_);  in _Pair()
151       return __begin_;  in begin()
155       return std::move(__begin_);  in begin()
164       return __begin_ == __end_;  in empty()
174         return std::__to_unsigned_like(__end_ - __begin_);  in size()
202           ranges::advance(__begin_, __n);  in advance()
209       auto __d = __n - ranges::advance(__begin_, __n, __end_);  in advance()