Reference

[Alexander Blinne]

Am 03.03.2014 19:48, schrieb Terry Reedy:
> The 'is' operator has three uses, two intended and one not. In
> production code, 'is' tests that an object *is* a particular singular
> object, such as None or a sentinel instance of class object.

Just a bit of statistics on this one from a recent small project:

<13:51:20> alex at firefly$ grep ' is ' *.py | wc
     65     415    3234
<13:51:35> alex at firefly$ grep ' is None' *.py | wc
     43     243    1948
<13:51:40> alex at firefly$ grep ' is not None' *.py | wc
     21     167    1241
<13:51:44> alex at firefly$ grep ' is False' *.py | wc
      1       5      45

No other uses if 'is' found in almost 3 KLOC...