input: Write a python function to parse a given string and extract the domain name.
  assert extract_domain_name('https://www.google.com/search?q=google+search') == 'www.google.com'
  assert extract_domain_name('http://example.com/') == 'example.com'
  assert extract_domain_name('ftp://my.ftp.server.com/path/to/file') == 'my.ftp.server.com'
  assert extract_domain_name('https://sub.domain.co.uk/path') == 'sub.domain.co.uk'
  assert extract_domain_name('no-protocol.com/path') == ''
output: def extract_domain_name(url):
      from urllib.parse import urlparse
  
      if '://' not in url:
          return ''
      
      parsed_url = urlparse(url)
      return parsed_url.netloc