How Can This Be Used?

[nevets04]

How would can you put this code to use?

Code:

x = "luck"
#replace the l in in luck with a d
y = x.replace("l", "d")
#Displays what y is equal to on the screen
print y

There is the code, but im thinking, why not just

Code:

print "duck"

So how would it be useful?