input: Write a function to parse a given URL and print out the protocol, domain name, and path using Python. The function should use the `urllib.parse` module to parse the URL and should return a tuple containing the protocol, domain name, and path.
  
  assert parse_url('https://www.example.com/path/to/file')==('https', 'www.example.com', '/path/to/file')
  assert parse_url('http://sub.domain.com/folder/file.html')==('http', 'sub.domain.com', '/folder/file.html')
  assert parse_url('ftp://ftp.server.com/some/path')==('ftp', 'ftp.server.com', '/some/path')
  assert parse_url('https://www.google.com')==('https', 'www.google.com', '/')
  assert parse_url('http://localhost:8080/index')==('http', 'localhost:8080', '/index')
output: def parse_url(url):
      from urllib.parse import urlparse
      parsed = urlparse(url)
      return (parsed.scheme, parsed.netloc, parsed.path)