code: def on_key_press(event):
      if event.key == "f":
          face_normals.visible = not face_normals.visible
          canvas.update()
      elif event.key == "v":
          vertex_normals.visible = not vertex_normals.visible
          canvas.update()
  
imports: from vispy import app, scene
  from vispy.io import read_mesh, load_data_file
  from vispy.scene.visuals import Mesh, MeshNormals
  from vispy.visuals.filters import WireframeFilter
label_desc: Use image node_id 1 for calling a global function with example usage: on_key_press(event) without return types