class_docstr: Represents a mouse event that occurred on a SceneCanvas. This event is
  delivered to all entities whose mouse interaction area is under the event.
docstr: The scale of a gesture_zoom event
docstr_tok: ["The","scale","of","a","gesture_zoom","event"]
code: def scale(self):
      """The scale of a gesture_zoom event"""
      try:
          return self.mouse_event.scale
      except AttributeError:
          errmsg = f"SceneMouseEvent type '{self.type}' has no scale"
          raise TypeError(errmsg)
  
file_path: vispy/vispy/scene/events.py
imports: from __future__ import division
  from ..util.event import Event
label_desc: Use image node_id 10 for calling the SceneMouseEvent obj's underlying member method code with example usage: obj.scale() and returns: self