Question: who wrote the preface to the english translation of gitanjali
[{'answer': 'William Butler Yeats', 'provenance': [{'wikipedia_id': '1849907', 'title': 'Gitanjali', 'start_paragraph_id': 7, 'start_character': 0, 'end_paragraph_id': 7, 'end_character': 20, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '1849907', 'title': 'Gitanjali', 'start_paragraph_id': 7, 'start_character': 0, 'end_paragraph_id': 7, 'end_character': 78, 'bleu_score': 0.8385766789076251, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10092591961953842140}, 'section': 'Section::::History.\n'}]}]