code: def loadFile(self, fileName):
          
  
          self.fileName = fileName
          # Assign QFile object with the current name.
          self.file = QtCore.QFile(fileName)
          if self.file.exists():
              # Load the file into the widget and reset the undo stack
              # to delete the undo object create by the setText method.
              # Without it, an undo operation would delete the content
              # of the widget which is intuitive.
              self.qteScintilla.setText(open(fileName).read())
              self.qteScintilla.qteUndoStack.reset()
          else:
              msg = "File <b>{}</b> does not exist".format(self.qteAppletID())
              self.qteLogger.info(msg)
docs: Display the file ``fileName``.