#include<ostream>// see [ostream.syn]namespace std {template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT>>class basic_syncbuf;
using syncbuf = basic_syncbuf<char>;
using wsyncbuf = basic_syncbuf<wchar_t>;
template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT>>class basic_osyncstream;
using osyncstream = basic_osyncstream<char>;
using wosyncstream = basic_osyncstream<wchar_t>;
}