code: def _prepare_draw(self, view):
      pass
  
file_path: vispy/examples/demo/scene/flow_lines.py
imports: from __future__ import division
  from vispy import app, scene, visuals, gloo
  from vispy.util import ptime
  import numpy
label_desc: Use image node_id 3 for calling the VectorFieldVisual obj's underlying member method code with example usage: obj._prepare_draw(view) without return types