Python Programming - Writing and Reading Files

print ("We are going to write and read a file. ")
keepgoing = "y"
while keepgoing == "y":
shortsent = input("Enter a short sentence. ")
# open a text file to append
openfile = open("testfile.txt", "a")
# write sentence to file
openfile.write(shortsent)
openfile.close()
keepgoing = input("Enter another? y or n: ")
print ("The sentence entered is: ", shortsent)

# open the file to read
openfile = open("testfile.txt")
# read the file into a variable
linesread = openfile.readlines()
print ("The file now reads: ", linesread)