code: def _init_readingListbox(self, parent):
      self._readingFrame = listframe = Frame(parent)
      self._readingFrame.pack(fill="both", side="left", padx=2)
      self._readingList_label = Label(
          self._readingFrame, font=self._boldfont, text="Readings"
      )
      self._readingList_label.pack()
      self._readingList = Listbox(
          self._readingFrame,
          selectmode="single",
          relief="groove",
          background="white",
          foreground="#909090",
          font=self._font,
          selectforeground="#004040",
          selectbackground="#c0f0c0",
      )
  
      self._readingList.pack(side="right", fill="both", expand=1)
  
      # Add a scrollbar if there are more than 25 examples.
      listscroll = Scrollbar(self._readingFrame, orient="vertical")
      self._readingList.config(yscrollcommand=listscroll.set)
      listscroll.config(command=self._readingList.yview)
      listscroll.pack(side="right", fill="y")
  
      self._populate_readingListbox()
  
imports: from nltk.parse import MaltParser
  from nltk.sem.drt import DrsDrawer, DrtVariableExpression
  from nltk.sem.glue import DrtGlue
  from nltk.sem.logic import Variable
  from nltk.tag import RegexpTagger
  from nltk.util import in_idle
label_desc: Use image node_id 5 for calling the DrtGlueDemo obj's underlying member method code with example usage: obj._init_readingListbox(parent) without return types