46 assert_valid(
const char* __file, 
int __line)
 const 
   48   size_type calc_size = 0;
 
   49   for (const_iterator it = 
begin(); it != 
end(); ++it)
 
   51       debug_base::check_key_exists(PB_DS_V2F(*it), __file, __line);
 
   54   debug_base::check_size(calc_size, __file, __line);
 
auto end(_Container &__cont) -> decltype(__cont.end())
Return an iterator pointing to one past the last element of the container. 
auto begin(_Container &__cont) -> decltype(__cont.begin())
Return an iterator pointing to the first element of the container.