explicit back_insert_iterator(Container& x);
Effects: Initializes container with std::addressof(x).
back_insert_iterator<Container>&
  operator=(const typename Container::value_type& value);
Effects: container->push_back(value);
Returns: *this.
back_insert_iterator<Container>&
  operator=(typename Container::value_type&& value);
Effects: container->push_back(std::move(value));
Returns: *this.
back_insert_iterator<Container>& operator*();
Returns: *this.
back_insert_iterator<Container>& operator++();
back_insert_iterator<Container>  operator++(int);
Returns: *this.
template <class Container>
  back_insert_iterator<Container> back_inserter(Container& x);
Returns: back_insert_iterator<Container>(x).