/// Extracts the item from the set with comparing functor \p pred
/**
- The function is an analog of \ref cds_nonintrusive_SkipListSet_rcu_extract "extract(exempt_ptr&, Q const&)"
- but \p pred predicate is used for key comparing.
+ The function is an analog of \p extract(Q const&) but \p pred predicate is used for key comparing.
\p Less has the semantics like \p std::less.
\p pred must imply the same element order as the comparator used for building the set.
*/