Call backs provided to the host application by the multi processor
framework.
This class allows for independence from the host
class/application.
Note:
The logic behind the design the callbacks are defined as two
attributes self.init_master and self.handle_exception as
handle_exception can be null (which is used to request the use of
the processors default error handling code). Note, however, that a
class with the equivalent methods would also works as python
effectively handles methods as attributes of a class. The
signatures for the callback methods are documented by the default
methods default_init_master & default_handle_exception.
