docs: def add_text(self, end, next=None):
          """
          Adds the text from string beginning to the specified ending
          index to the format.
  
          :param end: The ending index of the string.
          :param next: The next string begin index.  If None, the string
                       index will not be updated.
          """
  
          if self.str_begin != end:
              self.fmt.append_text(self.format[self.str_begin:end])
  
          if next is not None:
              self.str_begin = next