title: What is the purpose of Ref-qualified member functions ?
body: <p>While reading <a href="http://en.cppreference.com/w/cpp/language/member_functions" rel="noreferrer">http://en.cppreference.com/w/cpp/language/member_functions</a>, I came across something, I haven't seen before: <code>lvalue/rvalue Ref-qualified member functions</code>. What would be their purpose ?</p>