Pop up dialog from main app in Tkinter (python)

I'm am trying to create a pop up dialog in Tkinter from an application so that I can send values back from the dialog to the main screen.

This is part of the code:

from Tkinter import *
import ttk
class MainScreen:
def __init__(self, master):
self.master = master
self.result="Untested"

self.b = Button(master, text="Select Data", width=12)
self.b.grid(row=0, column=0)
self.b = Button(master, text="Select Learners", width=12, command=self.display_learner_options)
self.b.grid(row=0, column=1)
self.b = Button(master, text="Optimize",width=12)
self.b.grid(row=0, column=2)
self.b = Button(master, text="Save Results", width=12)
self.b.grid(row=0, column=3)
self.b = Button(master, text="Exit", width=12, command=quit)
self.b.grid(row=0, column=4)
self.t = Text(master, width=60, height=15)
self.t.grid(row=1, columnspan=5)
self.p = ttk.Progressbar(master)
self.p.grid(row=2, columnspan=5)
def display_learner_options(self):
self.learnerOptions = LearnerOptions(self.master)
class LearnerOptions(Toplevel):
def __init__(self, parent):
Toplevel.__init__(self, parent)
self.transient(parent)
self.parent = parent
self.b = Button(self, text="Test")
self.b.pack()
# self.grab__set()
self.initial_focus = self
self.wait__window(self)
def test(self):
parent.result="Tested"
self.destroy
root = Tk()
root.wm_title("Prediction Optimizer")
mainScreen = MainScreen(root)
root.mainloop()

I get the following exception:

LearnerOptions instance has no attribute wait_window

What am I doing wrong or omitting?

Thanks--Steve