code: def target(self):
          
          task = yield self.task()
          if not task:
              yield defer.succeed(None)
              defer.returnValue(None)
          defer.returnValue(task.target)
docs: Find the target name for this build.
  
          :returns: deferred that when fired returns the build task's target
                    name. If we could not determine the build task, or the task's
                    target, return None.