int main(void) {

  cons_cell *points, *more_points, *point_list, *pl;

  point p1 = {1,2}, p2 = {3,4}, p3 = {5,6}, p4 = {6,7},
        p5 = {8,9}, p6 = {10,11}, p7 = {12,13}, p8 = {14,15};

  points = cons(&p1,
                cons(&p2,
                     cons(&p3,
                          cons(&p4,NULL))));

  more_points = 
           cons(&p5,
                cons(&p6,
                     cons(&p7,
                          cons(&p8,NULL))));

  printf("Number of points in the list points: %i\n", 
         list_length(points));

  point_list = append(points, more_points);
  pl = point_list;

  while (pl != NULL) {
    prnt_point(*((point*)(head(pl))));
    pl = tail(pl);
  }

  if (member(&p6, points))
    printf("p6 is member of points\n");
  else  printf("p6 is NOT member of points\n");

  if (member(&p6, more_points))
    printf("p6 is member of more_points\n");
  else  printf("p6 is NOT member of more_points\n");

  if (member(&p6, point_list))
    printf("p6 is member of point_list\n");
  else  printf("p6 is NOT member of point_list\n");


  pl = reverse(points);

  while (pl != NULL) {
    prnt_point(*((point*)(head(pl))));
    pl = tail(pl);
  }
  
  return 0;
}