docs: def add_escape(self, idx, char):
          """
          Translates and adds the escape sequence.
  
          :param idx: Provides the ending index of the escape sequence.
          :param char: The actual character that was escaped.
          """
  
          self.fmt.append_text(self.fmt._unescape.get(
              self.format[self.str_begin:idx], char))