Question: who played the lead role in seinfeld on nbc until it ended in 1998
[{'answer': 'Jerry Seinfeld', 'provenance': [{'wikipedia_id': '28606', 'title': 'Seinfeld', 'start_paragraph_id': 1, 'start_character': 70, 'end_paragraph_id': 1, 'end_character': 84, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '28606', 'title': 'Seinfeld', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 647, 'bleu_score': 0.6592687481892361, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16893379511170394851}, 'section': 'Section::::Abstract.'}]}]