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 increment by which the mouse wheel has moved.
docstr_tok: ["The","increment","by","which","the","mouse","wheel","has","moved","."]
code: def delta(self):
      """The increment by which the mouse wheel has moved."""
      return self.mouse_event.delta
  
file_path: vispy/vispy/scene/events.py
imports: from __future__ import division
  from ..util.event import Event
label_desc: Use image node_id 9 for calling the SceneMouseEvent obj's underlying member method code with example usage: obj.delta() and returns: self