docs: def _path_pair(self, s):
          """Parse two paths separated by a space."""
          # TODO: handle a space in the first path
          if s.startswith(b'"'):
              parts = s[1:].split(b'" ', 1)
          else:
              parts = s.split(b' ', 1)
          if len(parts) != 2:
              self.abort(errors.BadFormat, '?', '?', s)
          elif parts[1].startswith(b'"') and parts[1].endswith(b'"'):
              parts[1] = parts[1][1:-1]
          elif parts[1].startswith(b'"') or parts[1].endswith(b'"'):
              self.abort(errors.BadFormat, '?', '?', s)
          return [_unquote_c_string(s) for s in parts]