None, False, True

Terry Reedy tjreedy at
Wed Sep 17 04:56:54 CEST 2003

"M-a-S" <NO-MAIL at> wrote in message
news:5MJ9b.13244$x21.9088 at
> I mean what are None, False and True? Are they just identifiers? Are
> variables defined in __builtins__? Are they literals? Are they
language "bricks"
> like "for" and "1"?

You are trying too hard ;-)

They are currently names in the builtin namespace bound to PyObjects,
just like all other builtin names.  That means that they can be
shadowed by global or local names, just like all other builtin names.

There is a proposal to change the status of None, and possibly, True
and False, sometime in the future.  Hence the warning (also issued
because reassignment of None is likely a mistake).

Terry J. Reedy

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