input: Write a function to store user data in a JSON file and retrieve it. The store_user_data function should take a dictionary as input and write it to 'user_data.json', and the get_user_data function should read and return the data from 'user_data.json'. Use the following format and provide assert tests to validate the functions:
  
  assert store_user_data({"Name": "Alice", "Age": 30, "City": "Los Angeles"})==None
  assert get_user_data()=={"Name": "Alice", "Age": 30, "City": "Los Angeles"}
  assert store_user_data({"Name": "Bob", "Age": 22, "City": "Chicago"})==None
  assert get_user_data()=={"Name": "Bob", "Age": 22, "City": "Chicago"}
output: def store_user_data(data):
      with open('user_data.json', 'w') as file:
          json.dump(data, file)
  
  def get_user_data():
      with open('user_data.json', 'r') as file:
          return json.load(file)