class_docstr: Base class for getting verified answer from a user.
  
  For this base class, accept any non-blank string.
class_docstr_tok: ["Base","class","for","getting","verified","answer","from","a","user",".","For","this","base","class",",","accept","any","non-blank","string","."]
docstr: Return non-blank entry or None.
code: def entry_ok(self):  # Example: usually replace.
      "Return non-blank entry or None."
      entry = self.entry.get().strip()
      if not entry:
          self.showerror("blank line.")
          return None
      return entry
  
imports: import importlib.util, importlib.abc
  import os
  import shlex
  from sys import executable, platform
  from tkinter import Toplevel, StringVar, BooleanVar, W, E, S
  from tkinter.ttk import Frame, Button, Entry, Label, Checkbutton
  from tkinter import filedialog
  from tkinter.font import Font
  from tkinter.simpledialog import _setup_dialog
label_desc: Use image node_id 5 for calling the Query obj's underlying member method code with example usage: obj.entry_ok() and returns: entry, None