def assertIsSubdomainOf(testCase, descendant, ancestor):
 testCase.assertTrue(dns._isSubdomainOf(descendant, ancestor), ('%r is not a subdomain of %r' % (descendant, ancestor)))

def assertIsSubdomainOf ( testCase , descendant , ancestor ) : testCase . assertTrue ( dns . _isSubdomainOf ( descendant , ancestor ) , ( '%r is not a subdomain of %r' % ( descendant , ancestor ) ) )
assert that c{descendant} *is* a subdomain of c{ancestor} .