code: def lemmatize(self, tokens):
          
          entries = self.entries
          forms_and_lemmas = self.forms_and_lemmas
  
          lemma_list = [x[0] for x in entries]
          """Provide a lemma for each token"""
          lemmatized = []
          for token in tokens:
              """check for a match between token and list of lemmas"""
              if token in lemma_list:
                  lemmed = (token, token)
                  lemmatized.append(lemmed)
              else:
                  """if no match check for a match between token and list of lemma forms"""
                  lemma = [k for k, v in forms_and_lemmas.items() if token in v]
                  if lemma != []:
                      lemmed = (token, lemma)
                      lemmatized.append(lemmed)
                  elif lemma == []:
                      """if no match apply regular expressions and check for a match against the list of lemmas again"""
                      regexed = regex(token)
                      if regexed in lemma_list:
                          lemmed = (token, regexed)
                          lemmatized.append(lemmed)
                      else:
                          lemmed = (token, "None")
                          lemmatized.append(lemmed)
          return lemmatized
docs: define list of lemmas