Question: who came up with the type of calculator known as 'the step reckoner'
[{'answer': 'German mathematician Gottfried Wilhelm Leibniz', 'provenance': [{'wikipedia_id': '2780664', 'title': 'Stepped reckoner', 'start_paragraph_id': 1, 'start_character': 92, 'end_paragraph_id': 1, 'end_character': 138, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '2780664', 'title': 'Stepped reckoner', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 375, 'bleu_score': 0.963949056609222, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7612341923496328021}, 'section': 'Section::::Abstract.'}]}]