Division by zero is always a problem. Update the preceding function to check if length is 0. If so, it should output an error message and return the special value None. Or you can use the statement:...

Division by zero is always a problem. Update the preceding function

to check if length is 0. If so, it should output an error message and

return the special value None. Or you can use the statement:

raise ZeroDivisionError(string)

where string contains the error message. This will result in a

typical Python error message similar to the ones we first saw in

Chapter 2.