code: int render(TokenBuilder builder, CharMatcher asLiteral)
    {
      char ch = (char) character;
      if (asLiteral.matches(ch))
      {
        builder.append(ch);
      }
      else
      {
        //TODO could normalize space end chars
        builder.append(sequence);
      }
      return sequence.length() - 1;
    }
docs: Render this escape.
  
  @param builder   The TokenBuilder to render into
  @param asLiteral If given matcher matches this escapes literal, then render as literal, else as escape.
  @return the length of the token in the input character stream