Again read the precondition for second$\_$in$\_$list. The second requirement is that s contains at least three items separated by commas. How would we assert that? Another way to say this precondition is that s must contain at least two commas.

Look at the string functions in the IntroCS API. Do you see something to help you here? Add this assert statement and then try it out in the interactive shell.

codio@mike$-$panther:~$/$workspace$/$exercise$2$$ python

$>>>$ import func

$>>>$ func.second$\_$in$\_$list$(\text{'}$apple$\text{'})$

If you did it correctly, this should crash and the first line of the error message should explicitly reference the line with the assert statement.