Question: when did joseph campbell create the hero's journey
[{'answer': '1949', 'provenance': [{'wikipedia_id': '908507', 'title': "Hero's journey", 'start_paragraph_id': 2, 'start_character': 472, 'end_paragraph_id': 2, 'end_character': 476, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '908507', 'title': "Hero's journey", 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 573, 'bleu_score': 0.940939793195775, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8909147222244704189}, 'section': 'Section::::Abstract.'}]}]