try:
raise TypeError
except TypeError:
try:
tb = sys.exc_info()[2]
TracebackType = type(tb)
FrameType = type(tb.tb_frame)
except AttributeError:
# In the restricted environment, exc_info returns (None, None,
# None) Then, tb.tb_frame gives an attribute error
pass
tb = None; del tb
我完全不明白這段代碼。它的目的是什麼?這些來自types.py的代碼是做什麼的?