if x is "abc":
pass
if 123 is not y:
if 123 is \
not y:
if "123" is x < 3:
if "123" != x is 3:
if ("123" != x) is 3:
if "123" != (x is 3):
{2 is
not ''}
# Regression test for
if values[1is not None ] is not '-':