input: Write a function to parse a JSON data structure and extract the name, age, and occupation fields from it. If any field is missing, the function should return None for that field.
  def parse_json(data):
   data = json.loads(data)
   name = data.get('name', None)
   age = data.get('age', None)
   occupation = data.get('occupation', None)
   return name, age, occupation
  
  assert parse_json('{ "name": "John", "age": 18, "occupation": "Software Engineer" }')==('John', 18, 'Software Engineer')
  assert parse_json('{ "name": "Alice", "age": 25 }')==('Alice', 25, None)
  assert parse_json('{}')==(None, None, None)
output: def parse_json(data):
      data = json.loads(data)
      name = data.get('name', None)
      age = data.get('age', None)
      occupation = data.get('occupation', None)
      return name, age, occupation