class X

	def main
		try
			assert 'a' not in 'ab'  # will fail
		catch exc as Exception
			# should pass
			assert "('a' not 'ab')" not in exc.message
			assert "('a' not in 'ab')" in exc.message
		a, b = 'x', 'xy'
		try
			assert a is not b  # will fail
		catch exc as Exception
			# should pass
			assert "('x' is 'xy')" not in exc.message
			assert "('x' is not 'xy')" in exc.message