input: Write a function to store and query user data in a JSON file. The function should be able to take a dictionary of user information, store it in a file named 'user_data.json', and retrieve the data from the file. If the file does not exist, it should return an empty dictionary.
  assert store_user_data({"Name": "John", "Age": 25, "City": "New York"})==None
  assert get_user_data()=={"Name": "John", "Age": 25, "City": "New York"}
  assert store_user_data({"Name": "Alice", "Age": 30, "City": "Los Angeles"})==None
  assert get_user_data()=={"Name": "Alice", "Age": 30, "City": "Los Angeles"}
  assert get_user_data() if not exists('user_data.json') else {}=={}
output: def store_user_data(user_info):
      with open('user_data.json', 'w') as file:
          json.dump(user_info, file)
  
  def get_user_data():
      if not os.path.exists('user_data.json'):
          return {}
      with open('user_data.json', 'r') as file:
          return json.load(file)