input: Write a python function to reformat a JSON string with sorted keys and indentation.
  assert reformat_json('{"name":"John","age":30,"city":"New York"}') == '{\n    "age": 30,\n    "city": "New York",\n    "name": "John"\n}'
  assert reformat_json('{"b":2,"a":1}') == '{\n    "a": 1,\n    "b": 2\n}'
  assert reformat_json('{"z":0,"y":1,"x":2}') == '{\n    "x": 2,\n    "y": 1,\n    "z": 0\n}'
output: import json
  
  def reformat_json(json_str):
      parsed_json = json.loads(json_str)
      return json.dumps(parsed_json, indent=4, sort_keys=True)