Question: how many seasons of when calls the heart are there
[{'answer': 'fifth season', 'provenance': [{'wikipedia_id': '41630866', 'title': 'When Calls the Heart', 'start_paragraph_id': 56, 'start_character': 119, 'end_paragraph_id': 56, 'end_character': 131, 'bleu_score': 1.0, 'section': 'Section::::Production.\n'}]}]