code: def tobuf(self, format=DEFAULT_FORMAT, encoding=ENCODING, errors="surrogateescape"):
          
          info = self.get_info()
  
          if format == USTAR_FORMAT:
              return self.create_ustar_header(info, encoding, errors)
          elif format == GNU_FORMAT:
              return self.create_gnu_header(info, encoding, errors)
          elif format == PAX_FORMAT:
              return self.create_pax_header(info, encoding)
          else:
              raise ValueError("invalid format")
docs: Return a tar header as a string of 512 byte blocks.