input: Write a function to parse a JSON data structure and extract the 'name', 'age', and 'occupation' fields from the given dictionary. If the dictionary is empty or does not contain one of these fields, return None for that field.
  assert parse_json({'name': 'John', 'age': 18, 'occupation': 'Software Engineer'}) == ('John', 18, 'Software Engineer')
  assert parse_json({'name': 'Jane', 'age': 22}) == ('Jane', 22, None)
  assert parse_json({}) == (None, None, None)
  assert parse_json({'name': 'Alice', 'occupation': 'Student'}) == ('Alice', None, 'Student')
  assert parse_json({'age': 30, 'occupation': 'Doctor'}) == (None, 30, 'Doctor')
output: def parse_json(data):
      name = data.get('name', None)
      age = data.get('age', None)
      occupation = data.get('occupation', None)
      return (name, age, occupation)