code: def on_key_press(ev):
      if ev.key.name in "+=":
          vb.camera.zoom_factor *= 1.1
      elif ev.key.name == "-":
          vb.camera.zoom_factor /= 1.1
      print("Zoom factor: %0.4f" % vb.camera.zoom_factor)
  
imports: import numpy
  import vispy.scene
  from vispy.scene import visuals
label_desc: Use image node_id 1 for calling a global function with example usage: on_key_press(ev) without return types