Function unwrap

include/fmt/args.h:26–26

struct is_reference_wrapper<std::reference_wrapper<T>> : std::true_type {};

template <typename T> auto unwrap(const T& v) -> const T& { return v; }
template <typename T>
auto unwrap(const std::reference_wrapper<T>& v) -> const T& {
  return static_cast<const T&>(v);