// https://stackoverflow.com/questions/2590677/how-do-i-combine-hash-values-in-c0x
#pragma once
#include <functional>

template<typename T, typename... Rest>
void hash_combine(std::size_t& seed, const T& v, const Rest&... rest)
{
  seed ^= std::hash<T>{}(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
  (hash_combine(seed, rest), ...);
}