Decorator that can track usage through exceptions

tracking_decorator.py

def a(throw_please=False):
    _ret = None
    _exc = None
    try:
        print("try")
        if throw_please:
            b = []
            b[1] = 3
        _ret = 4
    except Exception as exc:
        print("except")
        _exc = exc
        raise
    else:
        print("else")
        return _ret
    finally:
        print("finally fn_name: |{2}| ret: |{0}| exc: |{1}|".format(_ret, _exc, a.func_name))


print("a() = {0}".format(a(False)))
print("a() = {0}".format(a(True)))

"""
>>> print("a() = {0}".format(a(False)))
try
else
finally fn_name: |a| ret: |4| exc: |None|
a() = 4
>>> print("a() = {0}".format(a(True)))
try
except
finally fn_name: |a| ret: |None| exc: |list assignment index out of range|
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 8, in a
IndexError: list assignment index out of range
"""