code: def onPenChanging(self, param, val):
      self.pen = QtGui.QPen(val)
      self.update()
  
imports: from ..Qt import QtWidgets, QtGui, QtCore
  from ..functions import mkPen
label_desc: Use image node_id 2 for calling the PenPreviewLabel obj's underlying member method code with example usage: obj.onPenChanging(param, val) without return types