a new comment) suggests there are almost certainly large input
integers in all non-binary input bases for which one Python digit
too few is initally allocated to hold the final result.  Instead
of assert-failing when that happens, allocate more space.  Alas,
I estimate it would take a few days to find a specific such case,
so this isn't backed up by a new test (not to mention that such
a case may take hours to run, since conversion time is quadratic
in the number of digits, and preliminary attempts suggested that
the smallest such inputs contain at least a million digits).

subclasses of Exception can be supplied keyword args

I'm not sure this is the best approach, but I can't think of anything better.
If this creates problems, feel free to revert, but I think it's safe and
should make things a little better.

our lives taking turns rewriting code that works ;-),
get rid of casting illusions by declaring a new variable
with the obvious type.

from a (possibly) wider variable.

I don't have a box with nearly enough RAM, or an OS,
that could get close to tickling this, though (requires
a dict w/ at least 2**31 entries).

are run in the order:

    test_genexps (or any other doctest-based test)
    test_struct
    test_doctest

The `warnings` module needs an advertised way to save/restore
its internal filter list.

struct: modulo math plus warning on all endian-explicit formats for compatibility with older struct usage (ugly)

the current behaviour ;-)

Use Py_UnpackTuple instead of PyArg_ParseTuple where possible.

and watch out for handler name collisions.

Renames functional extension module to _functools and adds a Python
functools module so that utility functions like update_wrapper can be
added easily.