# Add the following lines to your `menu.py`
nuke.menu('Nuke').addCommand("Viewer/Uprez",   "nuke.activeViewer().node().knob('downrez').setValue(str(nuke.activeViewer().node().knob('downrez').getValue()-1))", "Alt+z")
nuke.menu('Nuke').addCommand("Viewer/Downrez", "nuke.activeViewer().node().knob('downrez').setValue(str(nuke.activeViewer().node().knob('downrez').getValue()+1))", "Alt+x")