title: Is there any position limitation on the insert hint for std::map?
body: <p>I just found std::map.insert could accept an iterator as its first parameter as a search hint for the insertion process, such as <code>map.insert(hintIterator, insertElement);</code>. But is there any position requirement for the hint element? Does it need to be just before or after the insert position?   By the way, how much effect does the hint iterator position have on the insertion efficiency? </p>