code: private boolean isNextEscape() throws
        IOException
    {
      boolean result = false;
      Mark mark = reader.mark();
      int ch = reader.next();
      if (ch == '\\')
      {
        try
        {
          Optional<CssEscape> esc = new CssEscape(reader, builder)
              .create();
          result = esc.isPresent();
        }
        catch (CssException ignore)
        {
  
        }
      }
      reader.unread(ch, mark);
      return result;
    }
docs: Returns true if reader next() is the start of a valid escape sequence.
  
  @return whether or not the reader is at the start of a valid escape sequence.
  @throws IOException