Chapter 3 Session 3.4

The last expression of Session 3.4 should be name[len(name)-1] not name[len(name)]. name[len(name)] generates a range error because the length of the string is 1 past the end of the string.

Chapter 3 -- Listing 3.12 Vignere cipher

Line 5 of Listing 3.12 contains the statement charNum = 0. The variable charNum is not used anywhere in the encryptVignere function and the line is not needed.

Line 2 is also extraneous. It contains the template docstring for the encryptVignere function.