code: def _prepare_draw(self, view):
      # attributes / uniforms are not available until program is built
      self.shared_program["a_position"] = VertexBuffer(self._pos)
      self.shared_program["a_color"] = VertexBuffer(self._color)
      self.shared_program["a_size"] = VertexBuffer(self._size)
  
file_path: vispy/examples/basics/visuals/custom_visual.py
imports: from __future__ import division
  import numpy
  from vispy import app
  from vispy.gloo import VertexBuffer
  from vispy.visuals import Visual
  from vispy.visuals.transforms import STTransform
label_desc: Use image node_id 3 for calling the MarkerVisual obj's underlying member method code with example usage: obj._prepare_draw(view) without return types