docstr: Return ordered list of modifiers that have been selected.
docstr_tok: ["Return","ordered","list","of","modifiers","that","have","been","selected","."]
code: def get_modifiers(self):
      "Return ordered list of modifiers that have been selected."
      mod_list = [variable.get() for variable in self.modifier_vars]
      return [mod for mod in mod_list if mod]
  
imports: from tkinter import Toplevel, Listbox, StringVar, TclError
  from tkinter.ttk import Frame, Button, Checkbutton, Entry, Label, Scrollbar
  from tkinter import messagebox
  from tkinter.simpledialog import _setup_dialog
  import string
  import sys
label_desc: Use image node_id 8 for calling the GetKeysFrame obj's underlying member method code with example usage: obj.get_modifiers() and returns: unknown