iterator insert( iterator i, const TYPE& val );
  void insert( input_iterator start, input_iterator end );
  iterator insert( const TYPE& val );

The function insert() either:
		

• inserts val after the element at pos (where pos is really just a suggestion as to where val should go, since multisets and multimaps are ordered), and returns an iterator to that element.
• inserts a range of elements from start to end.
• inserts val into the multiset. The return value is an iterator to the element inserted, and a boolean describing whether an insertion took place.