code: def on_draw(self, event):
      gloo.clear("black")
      self.line.draw()
  
file_path: vispy/examples/basics/visuals/line_plot.py
imports: import numpy
  import sys
  from vispy import gloo, app, visuals
label_desc: Use image node_id 2 for calling the Canvas obj's underlying member method code with example usage: obj.on_draw(event) without return types