class_docstr: Represents one of the three thumbnails at the top of the window.
code: def mousePressEvent(self, event):
      self.parent.set_large_image(self.index)
  
imports: import os
  from pathlib import Path
  import shutil
  import sys
  from matplotlib.backends.qt_compat import QtCore, QtGui, QtWidgets
  from matplotlib.backends.qt_compat import _exec
label_desc: Use image node_id 2 for calling the Thumbnail obj's underlying member method code with example usage: obj.mousePressEvent(event) without return types