Method insert

paddle/utils/small_vector.h:830–832

 public:
  iterator insert(iterator I, T &&Elt) {
    return insert_one_impl(I, this->forward_value_param(std::move(Elt)));
  }

  iterator insert(iterator I, const T &Elt) {
    return insert_one_impl(I, this->forward_value_param(Elt));