Use generator based builder to inherit free functionality

personachat_truecased.py

@@ -33,7 +33,7 @@ _CITATION = """\
 """
 
 
-class PersonachatTruecased(datasets.DatasetBuilder):
+class PersonachatTruecased(datasets.GeneratorBasedBuilder):
     """
     Version of the PersonaChat dataset that includes true-casing, normalized punctuation, and candidate distractor
     responses for each dialogue turn, for including a multiple choice regularzation loss while training.