only available if asserts are left in the code, in cases where they
can't be triggered from Python code.

longobject.c: also fix an ssize_t problem
  <a> could have been NULL, so hoist the size calc to not use <a>.

_ssl.c: under fail: self is DECREF'd, but it would have been NULL.

_elementtree.c: delete self if there was an error.

_csv.c: I'm not sure if lineterminator could have been anything other than
a string.  However, other string method calls are checked, so check this
one too.

using a custom, nearly-identical macro. This probably changes how some of
these functions are compiled, which may result in fractionally slower (or
faster) execution. Considering the nature of traversal, visiting much of the
address space in unpredictable patterns, I'd argue the code readability and
maintainability is well worth it ;P

available.

tp_clear methods.

In C++, it's an error to pass a string literal to a char* function
without a const_cast().  Rather than require every C++ extension
module to put a cast around string literals, fix the API to state the
const-ness.

I focused on parts of the API where people usually pass literals:
PyArg_ParseTuple() and friends, Py_BuildValue(), PyMethodDef, the type
slots, etc.  Predictably, there were a large set of functions that
needed to be fixed as a result of these changes.  The most pervasive
change was to make the keyword args list passed to
PyArg_ParseTupleAndKewords() to be a const char *kwlist[].

One cast was required as a result of the changes:  A type object
mallocs the memory for its tp_doc slot and later frees it.
PyTypeObject says that tp_doc is const char *; but if the type was
created by type_new(), we know it is safe to cast to char *.

this worked is a bit mystical.  Perhaps it never gets freed because the
object just happens never to be DECREF'd (but that seems unlikely).