input: Write a function to parse the given URL and print out the protocol, domain name, and path using Python. If the URL is empty, return a message indicating that the URL is invalid. Define the function as parse_url(url) and test it with the given example URL.
  assert parse_url('https://www.example.com/path/to/file')==['Protocol: https', 'Domain name: www.example.com', 'Path: /path/to/file']
  assert parse_url('http://test.com/some/path')==['Protocol: http', 'Domain name: test.com', 'Path: /some/path']
  assert parse_url('')==['Invalid URL']
output: def parse_url(url):
      if not url:
          return ['Invalid URL']
      from urllib.parse import urlparse
      parsed_url = urlparse(url)
      return [f'Protocol: {parsed_url.scheme}', f'Domain name: {parsed_url.netloc}', f'Path: {parsed_url.path}']