raise/from 捕获：打印异常上下文消息，指出新异常是由旧异常引起的，这样的异常之间的关联有助于后续对异常的分析和排查。（更规范）
>>> try:
... a=2/0
... except Exception as e:
... raise Exception('分母不能为0') from e
...
Traceback (most recent call last):
File "<stdin>", line 2, in <module>
ZeroDivisionError: division by zero
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "<stdin>", line 4, in <module>
Exception: 分母不能为0
>>>
raise from None：禁止/关闭自动显示异常上下文。
>>> try:
... a=2/0
... except Exception as e:
... raise Exception('分母不能为0') from None
...
Traceback (most recent call last):
File "<stdin>", line 4, in <module>
Exception: 分母不能为0
>>>
raise自定义异常中捕获：可同时抛出自定义异常和原生异常，但是无法体现异常的关联
>>> try:
... a=2/0
... except Exception as e:
... raise Exception(f'分母不能为0，{e}')
...
Traceback (most recent call last):
File "<stdin>", line 2, in <module>
ZeroDivisionError: division by zero
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "<stdin>", line 4, in <module>
Exception: 分母不能为0，division by zero
>>>
只raise抛出原生异常：只抛出原生异常
>>> try:
... a=2/0
... except Exception as e:
... raise e
...
Traceback (most recent call last):
File "<stdin>", line 4, in <module>
File "<stdin>", line 2, in <module>
ZeroDivisionError: division by zero
>>>
只raise自定义异常：可同时抛出自定义异常和原生异常，但是无法体现异常的关联
>>> try:
... a=2/0
... except Exception as e:
... raise Exception('分母不能为0')
...
Traceback (most recent call last):
File "<stdin>", line 2, in <module>
ZeroDivisionError: division by zero
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "<stdin>", line 4, in <module>
Exception: 分母不能为0
>>>
