docs: def _setup_source_and_destination(self):
          """use the base class to setup the source and destinations but add to
          that setup the instantiation of the "new_crash_source" """
          super(FetchTransformSaveWithSeparateNewCrashSourceApp, self) \
              ._setup_source_and_destination()
          if self.config.new_crash_source.new_crash_source_class:
              self.new_crash_source = \
                  self.config.new_crash_source.new_crash_source_class(
                      self.config.new_crash_source,
                      name=self.app_instance_name,
                      quit_check_callback=self.quit_check
                  )
          else:
              # the configuration failed to provide a "new_crash_source", fall
              # back to tying the "new_crash_source" to the "source".
              self.new_crash_source = self.source