code: def strip_empty_lines_backward(self, model, max_lines_to_strip):
          
          for l in range(0, max_lines_to_strip):
              if model[-1][0].strip(' \r\n\t\f') != '':
                  return
              self.debug_print_strip_msg(model[-1][1] - 1, model[-1][0])
              model.pop()
docs: Strips empty lines preceding the line that is currently being parsed. This
          fucntion is called when the parser encounters a Footer.
          :param model: lines that were added to the model up to this point
          :param line_num: the number of teh line being parsed
          :param max_lines_to_strip: max number of lines to strip from the model
          :return: None