In my game, I have an __init__ function which creates a set of seven entry boxes, like so:
self.string1 = StringVal()
self.entry1 = Entry(frame, textvariable = self.string1).grid(row = 4, column = 1, sticky = W)
This is copied six more times. This works. At the end of the game, though, I want to delete the Entry box's text, using this code I found several places online:
self.entry1.delete(0, END)
I also tried using something else I found:
if self.entry1.get():
    self.entry1.delete(0, END)
These both say that self.entry1 is a NoneType object, and has no method .get() or .delete(). Just to try things out, I substituted self.entry1.get() and self.entry1.delete(0,END) with self.string1.get(), etc. I also tried substituting .delete(0, END) with .delete(0.0, END). Neither of these worked either. I do not understand what I am doing wrong. 
Thanks for your help!