Function include

src/core/container_func.hpp:24–29

 */
template <typename Container>
inline bool include(Container &container, typename Container::const_reference &item)
{
	const bool is_member = std::ranges::find(container, item) != container.end();
	if (!is_member) container.emplace_back(item);
	return is_member;
}

/**
 * Helper function to get the index of an item