# function goes here


# checks that user response is not blank
def not_blank(question):

   while True:
       response = input(question)
       if response == "":
           print("Sorry this can't be blank. Please try again")
       else :
           return response


# main routine goes here
while True:
   name = not_blank("Enter your name (or 'xxx' to quit) ")
   if name == "xxx":
       break


print("We are done")