exception.py

class MyException(Exception):
    pass

class MyException2(Exception):
    pass


def f1():
    raise MyException('helllo')


try:
    f1()
except MyException as e:
    raise MyException2('howdy', e)

results

Traceback (most recent call last):
  File "et.py", line 17, in <module>
    raise MyException2('howdy', e)
__main__.MyException2: ('howdy', MyException('helllo',))