The subscriber ZCML directive configures an subscriber
callable to listen for events broadcast by the Pyramid web
- The class or interface that you are subscribing the listener for,
e.g. pyramid.events.NewRequest. Registering a subscriber for a
specific class or interface limits the event types that the subscriber
will receive to those specified by the interface or class. Default:
zope.interface.Interface (implying any event type).
- A dotted Python name which references an event handler
callable. The callable should accept a single argument: event.
The return value of the callable is ignored.