We want to join rvalues (see https://github.com/ericniebler/stl2/issues/598#issuecomment-545207308), so the name of _`ref-is-glvalue`_ is deceptive. I suggest renaming it to _`deref-is-ref`_.
We want to join rvalues (see ericniebler/stl2#598 (comment)), so the name of
ref-is-glvalueis deceptive. I suggest renaming it toderef-is-ref.