docs: private final boolean is_2_single_quotes_helper() throws IOException
      {
          int c = read_char();
          if (c != '\'') {
              unread_char(c);
              return false;
          }
          c = read_char();
          if (c != '\'') {
              unread_char(c);
              unread_char('\'');
              return false;
          }
          return true;
      }