text: #include<string_view>
  #include<fast_io.h>
  #include<fast_io_device.h>
  #include<fast_io_crypto.h>
  
  int main()
  {
  	fast_io::net_service serivce;
  	fast_io::native_socket_file socket(fast_io::tcp_listen(2000));
  	fast_io::sha256_context ctx;//use sha256 to prevent zero-copy transmission
  	fast_io::native_file logs(u8"log.txt",fast_io::open_mode::out);
  	for(fast_io::u8ibuf_file soc;;)//should work directly on unix like OS
  	{
  		try
  		{
  			soc.reopen(fast_io::tcp_accept(socket));
  			for(std::u8string_view line:line_scanner(soc))
  			{
  				println(::fast_io::mnp::u8as_file(ctx),line);
  			}
  			soc.close();
  			println("sha256:",fast_io::mnp::hash_digest(ctx));
  		}
  		catch(...)
  		{
  			perrln(logs,std::source_location::current());
  		}
  	}
  	return 0;
  }
  