Exercise 6.1 Write a while loop that starts at the last character in the string and works its
way backwards to the first character in the string, printing each letter on a separate line, except
backwards.
fruit='banana'
i=len(fruit)
while i>0:
    print fruit[i-1],'\n'
    i=i-1

Exercise 6.2 Given that fruit is a string, what does fruit[:] mean?
fruit='banana'
print fruit[:]
Types the full string