python - ('a' in 'abc' == True) evaluates to False -

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this question has answer here:

this got while fiddling python interpreter 

[mohamed@localhost ~]$ python python 2.7.5 (default, apr 10 2015, 08:09:14)  [gcc 4.8.3 20140911 (red hat 4.8.3-7)] on linux2 type "help", "copyright", "credits" or "license" more information. >>> 'a' in 'abc' true >>> 'a' in 'abc' == true false >>> 'a' in 'abc' == false false  >>> ('a' in 'abc') == true true >>> ('a' in 'abc') == false false   >>> ('a' in 'abc' == true) or ('a' in 'abc' == false) false >>> (('a' in 'abc') == true) or (('a' in 'abc') == false) true

my question why using parenthesis gives me intended, , more logically sound, output?

because of operator chaining, in , == not behave together.

'a' in 'abc' == true

transforms -

'a' in 'abc' , 'abc' == true

reference documentation -

comparisons can chained arbitrarily, e.g., x < y <= z equivalent x < y , y <= z , except y evaluated once (but in both cases z not evaluated @ when x < y found false).

the similar thing happens in , == .


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