#include <initializer_list>
namespace std {
template <class T, class Allocator = allocator<T>> class forward_list;
template <class T, class Allocator>
bool operator==(const forward_list<T, Allocator>& x, const forward_list<T, Allocator>& y);
template <class T, class Allocator>
bool operator< (const forward_list<T, Allocator>& x, const forward_list<T, Allocator>& y);
template <class T, class Allocator>
bool operator!=(const forward_list<T, Allocator>& x, const forward_list<T, Allocator>& y);
template <class T, class Allocator>
bool operator> (const forward_list<T, Allocator>& x, const forward_list<T, Allocator>& y);
template <class T, class Allocator>
bool operator>=(const forward_list<T, Allocator>& x, const forward_list<T, Allocator>& y);
template <class T, class Allocator>
bool operator<=(const forward_list<T, Allocator>& x, const forward_list<T, Allocator>& y);
template <class T, class Allocator>
void swap(forward_list<T, Allocator>& x, forward_list<T, Allocator>& y)
noexcept(noexcept(x.swap(y)));
namespace pmr {
template <class T>
using forward_list = std::forward_list<T, polymorphic_allocator<T>>;
}
}