Question: when did the first black player play in the nfl
[{'answer': 'Fritz Pollard', 'provenance': [{'wikipedia_id': '335603', 'title': 'Black players in professional American football', 'start_paragraph_id': 4, 'start_character': 391, 'end_paragraph_id': 4, 'end_character': 404, 'bleu_score': 1.0, 'section': 'Section::::Early years.\n'}]}, {'answer': 'Bobby Marshall', 'provenance': [{'wikipedia_id': '335603', 'title': 'Black players in professional American football', 'start_paragraph_id': 4, 'start_character': 409, 'end_paragraph_id': 4, 'end_character': 423, 'bleu_score': 1.0, 'section': 'Section::::Early years.\n'}]}, {'provenance': [{'wikipedia_id': '335603', 'title': 'Black players in professional American football', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 657, 'bleu_score': 0.9579655027162681, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17306260486797782117}, 'section': 'Section::::Early years.\n'}]}]