#include <iostream>
 
struct int_wrapper { int i ; /* .... */ } ;
 
std::ostream& print( const int_wrapper& w ) { return std::cout << '{' << w.i << "} " ; }
 
std::ostream& print_all() { return std::cout << '\n' ; }
 
template < typename... T > std::ostream& print_all( const int_wrapper& first, const T&... rest )
{
     print(first) ;
     return print_all( rest... ) ;
}
 
int main()
{
    int_wrapper a{0}, b{1}, c{2}, d{3} ;
    print_all() ;
    print_all( a ) ;
    print_all( a, b ) ;
    print_all( a, b, c ) ;
    print_all( a, b, c, d ) ;
}
 

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