Python 内置异常类的层次结构：
BaseException
±- SystemExit
±- KeyboardInterrupt
±- GeneratorExit
±- Exception
±- StopIteration
±- ArithmeticError
| ±- FloatingPointError
| ±- OverflowError
| ±- ZeroDivisionError
±- AssertionError
±- AttributeError
±- BufferError
±- EOFError
±- ImportError
±- LookupError
| ±- IndexError
| ±- KeyError
±- MemoryError
±- NameError
| ±- UnboundLocalError
±- OSError
| ±- BlockingIOError
| ±- ChildProcessError
| ±- ConnectionError
| | ±- BrokenPipeError
| | ±- ConnectionAbortedError
| | ±- ConnectionRefusedError
| | ±- ConnectionResetError
| ±- FileExistsError
| ±- FileNotFoundError
| ±- InterruptedError
| ±- IsADirectoryError
| ±- NotADirectoryError
| ±- PermissionError
| ±- ProcessLookupError
| ±- TimeoutError
±- ReferenceError
±- RuntimeError
| ±- NotImplementedError
±- SyntaxError
| ±- IndentationError
| ±- TabError
±- SystemError
±- TypeError
±- ValueError
| ±- UnicodeError
| ±- UnicodeDecodeError
| ±- UnicodeEncodeError
| ±- UnicodeTranslateError
±- Warning
±- DeprecationWarning
±- PendingDeprecationWarning
±- RuntimeWarning
±- SyntaxWarning
±- UserWarning
±- FutureWarning
±- ImportWarning
±- UnicodeWarning
±- BytesWarning
±- ResourceWarning