code: def zoom(self, value):
      if isinstance(value, Variable):
          self._zoom = value
          self._shader_map["zoom"] = self._zoom
      elif isinstance(self._zoom, Variable):
          self._zoom.value = value
      else:
          raise NotImplementedError()
  
imports: import numpy
  import math
  from vispy import gloo, app, scene
  from vispy.visuals import Visual
  from vispy.visuals.shaders import Function, Variable
  from vispy.visuals.transforms import TransformSystem, BaseTransform
  from vispy.util.profiler import Profiler
label_desc: Use image node_id 5 for calling the PanZoomTransform obj's underlying member method code with example usage: obj.zoom(value) without return types