      \param pos Index of the insertion.
      \param is_shared Tells if inserted images are shared copies of images of \c list or not.
    **/
    template<typename t>
    CImgList<T>& insert(const unsigned int n, const CImgList<t>& list, const unsigned int pos=~0U,
                        const bool is_shared=false) {
      if (!n) return *this;
Unknown