Python keyword and and or usage instances

And the expression is evaluated from left to right in Python, and if all values are true, the last value is returned, and if there is a false, the first false value is returned.

The or is also left-to-right with a computed expression, returning the first true value.
Copy the Code code as follows:

IDLE 1.2.4
>>> ' A ' and ' B '
' B '
>>> ' and ' B '
''
>>> ' A ' or ' B '
A
>>> ' or ' B '
' B '

Similar to the use of a trinocular expression: bool? A:b
Copy the Code code as follows:

>>> a = ' first '
>>> B = ' second '
>>>1and A or B # is equivalent to the case of bool = True
' First '
>>>0and A or B # is equivalent to the case of bool = False
' Second '
>>> a = ' '
The problem occurs when >>>1and A or B # A is False
' Second '
>>> (1and[a]or[b]) [0]# safe usage, because [a] cannot be false, at least one element
''
>>>

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