as you can see'forty twoisalpha(will return false because 'forty twohas space in itwhich is non-letter character 'fortytwoisalpha(returns true because it doesn' have this space ' isalpha(returns false because both ' and ' are non-letter characters isalpha(only returns true if the string has only letter characters and isn' blank the isalpha(method is used in the next few lines of the program for symbol in messageif symbol isalpha()num ord(symbolnum +key line ' for loop iterates over each letter (in cryptography they are called symbolsin the message string on each iteration through this loopsymbol will have the value of letter in message line is there because only letters will be encrypted or decrypted numberspunctuation marksand everything else will stay in their original form the num variable will hold the integer ordinal value of the letter stored in symbol line then "shiftsthe value in num by the value in key the isupper(and islower(string methods the isupper(and islower(string methods (which are on line and work in way that is similar to the isdigit(and isalpha(methods isupper(will return true if the string it is called on contains at least one uppercase letter and no lowercase letters islower(returns true if the string it is called on contains at least one lowercase letter and no uppercase letters otherwise these methods return false try entering the following into the interactive shell'helloisupper(true 'helloisupper(false 'helloislower(true 'helloislower(false 'look out behind you!isupper(true ' isupper(false post questions to