Question: who developed the concept of an iron law of wages
[{'answer': 'Ferdinand Lassalle', 'provenance': [{'wikipedia_id': '303067', 'title': 'Iron law of wages', 'start_paragraph_id': 1, 'start_character': 211, 'end_paragraph_id': 1, 'end_character': 229, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '303067', 'title': 'Iron law of wages', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 204, 'bleu_score': 0.9402297675816911, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7732284274697987963}, 'section': 'Section::::Lassalle.\n'}]}]