input: Write a function to get the domain name from an email address.
  assert get_domain_name_from_email('user@example.com') == 'example.com'
  assert get_domain_name_from_email('contact@domain.org') == 'domain.org'
  assert get_domain_name_from_email('name@subdomain.company.net') == 'subdomain.company.net'
output: def get_domain_name_from_email(email):
      return email.split('@')[1]