Question: where does hydrogen come from in the haber process
[{'answer': 'methane from natural gas', 'provenance': [{'wikipedia_id': '14022', 'title': 'Haber process', 'start_paragraph_id': 14, 'start_character': 32, 'end_paragraph_id': 14, 'end_character': 56, 'bleu_score': 1.0, 'section': 'Section::::Process.:Sources of hydrogen.\n'}]}, {'provenance': [{'wikipedia_id': '14022', 'title': 'Haber process', 'start_paragraph_id': 14, 'start_character': 0, 'end_paragraph_id': 14, 'end_character': 256, 'bleu_score': 0.9529077664391161, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7457871429453205597}, 'section': 'Section::::Process.:Sources of hydrogen.\n'}]}]