\endcode
where \p item is the item found, \p key is the <tt>find</tt> function argument.
- You may pass \p f argument by reference using \p std::ref.
-
The functor may change non-key fields of \p item. Note that the functor is only guarantee
that \p item cannot be disposed during functor is executing.
The functor does not serialize simultaneous access to the set's \p item. If such access is