22 General utilities library [utilities]
namespace std {
  template<class Context, class... Args>
  class format-arg-store {                                      
    array<basic_format_arg<Context>, sizeof...(Args)> args;     
  };
}
An instance of 
format-arg-store stores formatting arguments
.Preconditions: The type
typename Context::template formatter_type<remove_const_t<Ti>>
meets the 
BasicFormatter requirements (
[formatter.requirements])
for each 
Ti in 
Args. Returns: An object of type 
format-arg-store<Context, Args...>
whose 
args data member is initialized with
{basic_format_arg<Context>(fmt_args)...}. Effects: Equivalent to:
return make_format_args<wformat_context>(args...);