Add value of Entity as None if not available in story

{'intent': {'name': 'reminder', 'confidence': 0.7890547285867484}, 'entities': [{'start': 0, 'end': 3, 'value': 'add', 'entity': 'action', 'confidence': 0.7908196570499199, 'extractor': 'ner_crf'}, {'start': 4, 'end': 10, 'value': 'reminder', 'entity': 'tag', 'confidence': 0.6884967987186512, 'extractor': 'ner_crf', 'processors': ['ner_synonyms']}, {'start': 15, 'end': 23, 'value': 'birthday', 'entity': 'type', 'confidence': 0.8760218106577189, 'extractor': 'ner_crf'}], 'intent_ranking': [{'name': 'reminder', 'confidence': 0.7890547285867484}, {'name': 'quotes', 'confidence': 0.16370194851763384}, {'name': 'joke', 'confidence': 0.04724332289561807}], 'text': 'add reminder for birthday'}

i got above extracted data, if action entity not present then assign None. like

{‘action’: None, ‘tag’: ‘reminder’, ‘type’: ‘birthday’}