code: function stringify(value, code, attr, tag) {
    var s = open(code, attr);
    s +=  close(value, tag);
    return s;
  }
docs: Low-level method for creating escaped string sequences.
  
  @param value The value to escape.
  @param code The color code.
  @param attr An optional attribute code.
  @param tag A specific closing tag to use.