Insert into this multimap a value_type object created from the specified value. If a range containing elements equivalent to value_type object already exists, insert the value_type object at the end of that range. Return an iterator referring to the newly inserted value_type object. This method requires that the (template parameter) types KEY and VALUE both be move‐insertable into this multimap (see {Requirements on KEY and VALUE}), and the value_type be constructible from the (template parameter) ALT_VALUE_TYPE.