gistfile1.txt

import logging

logging.basicConfig(level=5)

from taskflow import engines as eng
from taskflow.patterns import linear_flow as lf
from taskflow import task
class MyTask(task.Task):
    def execute(self):
        raise ValueError('foo')
    def revert(self, *a, **k):
        raise ValueError('bar')


class HappyTask(task.Task):
    def execute(self):
        pass

    def revert(self, *a, **k):
        print("undoing")

flo = lf.Flow("test")
flo.add(HappyTask())
flo.add(MyTask())
eng.run(flo)