code: def dale_chall(self, diff_count, words, sentences):
          
          pdw = diff_count / words * 100
          asl = words / sentences
          raw = 0.1579 * (pdw) + 0.0496 * asl
          if pdw > 5:
              return raw + 3.6365
          return raw
docs: Calculate Dale-Chall readability score.