Module builtins

Compatibility idioms for __builtin__ names

This module adds names to the __builtin__ module for things that we want
to use in SCons but which don't show up until later Python versions than
the earliest ones we support.

This module checks for the following __builtin__ names:

        all()
        any()
        bool()
        dict()
        True
        False
        zip()

Implementations of functions are *NOT* guaranteed to be fully compliant
with these functions in later versions of Python.  We are only concerned
with adding functionality that we actually use in SCons, so be wary
if you lift this code for other uses.  (That said, making these more
nearly the same as later, official versions is still a desirable goal,
we just don't need to be obsessive about it.)

If you're looking at this with pydoc and various names don't show up in
the FUNCTIONS or DATA output, that means those names are already built in
to this version of Python and we don't need to add them from this module.

Demote a value to 0 or 1, depending on its truth value.

This is not to be confused with types.BooleanType, which is
way too hard to duplicate in early Python versions to be
worth the trouble.

Emulates the behavior we need from the built-in zip() function
added in Python 2.2.

Returns a list of tuples, where each tuple contains the i-th
element rom each of the argument sequences.  The returned
list is truncated in length to the length of the shortest
argument sequence.