import json
with open('test.json', 'r') as f:
	data = json.load(f)
	for items in data:
		items["1"] += [1, 2]
with open('test.json', 'w') as f:
	json.dump(data, f, indent=3)[
   {
      "1": []
   },
   {
      "2": []
   }
]items["1"] += [1, 2]
KeyError: '1'