import backoff

i: int = 0
@backoff.on_exception(backoff.expo, [ValueError])
def _retry():
    global i
    i += 1
    print(f"i = {i}")
    if i < 3:
        raise ValueError(f"failure {i}")
    if i == 3:
        raise RuntimeError("runtime error")

    return "success"

_retry()

i = 1
Traceback (most recent call last):
  File "/Users/davidslater/git/litl/backoff/backoff/_sync.py", line 107, in retry
    ret = target(*args, **kwargs)
  File "/Users/davidslater/git/litl/backoff/script.py", line 10, in _retry
    raise ValueError(f"failure {i}")
ValueError: failure 1

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/davidslater/git/litl/backoff/script.py", line 16, in <module>
    _retry()
  File "/Users/davidslater/git/litl/backoff/backoff/_sync.py", line 108, in retry
    except exception as e:
TypeError: catching classes that do not inherit from BaseException is not allowed