code: def update(ev):
      global pos, color, line
      pos[:, 1] = np.random.normal(size=N)
      color = np.roll(color, 1, axis=0)
      line.set_data(pos=pos, color=color)
  
imports: import sys
  import numpy
  from vispy import app, scene
label_desc: Use image node_id 1 for calling a global function with example usage: update(ev) without return types