In file included from main.cpp:1:0:
solution.h:4:8: error: 'vector' in namespace 'std' does not name a template type
   std::vector<iterator_traits<Iter>::value_type> elements;
        ^~~~~~
solution.h:6:41: error: ISO C++ forbids declaration of 'Slicer' with no type [-fpermissive]
     explicit Slicer(Iter begin, Iter end) {
                                         ^
solution.h:6:5: error: only declarations of constructors and conversion operators can be 'explicit'
     explicit Slicer(Iter begin, Iter end) {
     ^~~~~~~~
solution.h:13:5: error: 'size_t' does not name a type; did you mean '__size_t'?
     size_t size() const {
     ^~~~~~
     __size_t
solution.h:28:2: error: expected ';' after class definition
 }
  ^
  ;
solution.h: In member function 'int Page<Iter>::Slicer(Iter, Iter)':
solution.h:8:13: error: 'elements' was not declared in this scope
             elements.push_back(*begin);
             ^~~~~~~~
solution.h:11:5: error: no return statement in function returning non-void [-Werror=return-type]
     }
     ^
solution.h: In member function 'auto Page<Iter>::get()':
solution.h:18:16: error: 'elements' was not declared in this scope
         return elements;
                ^~~~~~~~
solution.h: In member function 'auto Page<Iter>::begin()':
solution.h:22:16: error: 'elements' was not declared in this scope
         return elements.begin();
                ^~~~~~~~
solution.h: In member function 'auto Page<Iter>::end()':
solution.h:26:16: error: 'elements' was not declared in this scope
         return elements.end();
                ^~~~~~~~
solution.h: At global scope:
solution.h:33:8: error: 'vector' in namespace 'std' does not name a template type
   std::vector<Page> pages;
        ^~~~~~
solution.h:45:5: error: 'size_t' does not name a type; did you mean '__size_t'?
     size_t size() const {
     ^~~~~~
     __size_t
solution.h:56:2: error: expected ';' after class definition
 }
  ^
  ;
solution.h: In constructor 'Slicer<Iter>::Slicer(Iter, Iter, int)':
solution.h:37:21: error: 'distance' is not a member of 'std'
         while (std::distance(begin, end) >= page_size) {
                     ^~~~~~~~
solution.h:38:13: error: 'pages' was not declared in this scope
             pages.push_back(Page(begin, i).get());
             ^~~~~
solution.h:38:13: note: suggested alternative: 'Page'
             pages.push_back(Page(begin, i).get());
             ^~~~~
             Page
solution.h:42:9: error: 'pages' was not declared in this scope
         pages.push_back(Page(begin, end).get());
         ^~~~~
solution.h:42:9: note: suggested alternative: 'Page'
         pages.push_back(Page(begin, end).get());
         ^~~~~
         Page
solution.h: In member function 'auto Slicer<Iter>::begin()':
solution.h:50:16: error: 'pages' was not declared in this scope
         return pages.begin();
                ^~~~~
solution.h:50:16: note: suggested alternative: 'Page'
         return pages.begin();
                ^~~~~
                Page
solution.h: In member function 'auto Slicer<Iter>::end()':
solution.h:54:16: error: 'pages' was not declared in this scope
         return pages.end();
                ^~~~~
solution.h:54:16: note: suggested alternative: 'Page'
         return pages.end();
                ^~~~~
                Page
solution.h: At global scope:
solution.h:58:1: error: expected unqualified-id before '<' token
 < template T >
 ^
In file included from /usr/include/c++/7/cassert:44:0,
                 from main.cpp:12:
main.cpp: In function 'void TestPageCounts()':
main.cpp:25:10: error: 'Slice' was not declared in this scope
   assert(Slice(v, 1).size() == v.size());
          ^
main.cpp:25:10: note: suggested alternative: 'Slicer'
main.cpp: In function 'void TestLooping()':
main.cpp:40:27: error: 'void __for_begin' has incomplete type
   for (const auto& page : slice_v) {
                           ^~~~~~~
main.cpp:40:27: error: 'void __for_end' has incomplete type
main.cpp:41:18: error: unable to deduce 'auto&&' from 'page'
     for (int x : page) {
                  ^~~~
main.cpp: In function 'void TestModification()':
main.cpp:52:20: error: 'Slice' was not declared in this scope
   for (auto page : Slice(vs, 2)) {
                    ^~~~~
main.cpp:52:20: note: suggested alternative: 'Slicer'
   for (auto page : Slice(vs, 2)) {
                    ^~~~~
                    Slicer
main.cpp:53:23: error: unable to deduce 'auto&&' from 'page'
     for (auto& word : page) {
                       ^~~~
main.cpp: In function 'void TestPageSizes()':
main.cpp:67:27: error: 'void __for_begin' has incomplete type
   for (const auto& page : letters_slices) {
                           ^~~~~~~~~~~~~~
main.cpp:67:27: error: 'void __for_end' has incomplete type
main.cpp: In function 'void TestConstContainer()':
main.cpp:79:27: error: 'Slice' was not declared in this scope
   for (const auto& page : Slice(letters, 10)) {
                           ^~~~~
main.cpp:79:27: note: suggested alternative: 'Slicer'
   for (const auto& page : Slice(letters, 10)) {
                           ^~~~~
                           Slicer
main.cpp: In function 'void TestPagination()':
main.cpp:92:33: error: 'Slice' was not declared in this scope
   for (const auto& split_by_9 : Slice(v, 9)) {
                                 ^~~~~
main.cpp:92:33: note: suggested alternative: 'Slicer'
   for (const auto& split_by_9 : Slice(v, 9)) {
                                 ^~~~~
                                 Slicer
main.cpp:95:23: error: unable to deduce 'auto&&' from 'split_by_4'
       for (int item : split_by_4) {
                       ^~~~~~~~~~
cc1plus: all warnings being treated as errors