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// add_const example
#include <iostream>
#include <type_traits>
int main() {
  typedef std::add_const<int>::type A;         // const int
  typedef std::add_const<const int>::type B;   // const int     (unchanged)
  typedef std::add_const<const int*>::type C;  // const int* const
  typedef std::add_const<int* const>::type D;  // int* const    (unchanged)
  typedef std::add_const<const int&>::type E;  // const int&    (unchanged)
  std::cout << std::boolalpha;
  std::cout << "checking constness:" << std::endl;
  std::cout << "A: " << std::is_const<A>::value << std::endl;
  std::cout << "B: " << std::is_const<B>::value << std::endl;
  std::cout << "C: " << std::is_const<C>::value << std::endl;
  std::cout << "D: " << std::is_const<D>::value << std::endl;
  std::cout << "E: " << std::is_const<E>::value << std::endl;
  return 0;
}
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