is still present in the containing structure.

attribute of an empty cell object.  Now a ValueError is raised.

backwards compatibility. Add Py_Refcnt, Py_Type, Py_Size, and
PyVarObject_HEAD_INIT.

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

tp_clear methods.

cell object. Now, a ``cell_contents`` attribute has been added
(closes patch #1170323).

into a hardcoded char* buffer.

Closes patch #454743.

with free variables.  Thanks to Martin v. Loewis for finding two of
the problems.  This fixes SF buf 405583.

There is also a C API change: PyFrame_New() is reverting to its
pre-2.1 signature.  The change introduced by nested scopes was a
mistake.  XXX Is this okay between beta releases?

cell_clear(), the GC helper, must decref its reference to break
cycles.

frame_dealloc() must dealloc all cell vars and free vars in addition
to locals.

eval_code2() setup code must INCREF cells it copies out of the
closure.

The STORE_DEREF opcode implementation must DECREF the object it passes
to PyCell_Set().

A cell contains a reference to a single PyObject.  It could be
implemented as a mutable, one-element sequence, but the separate type
has less overhead.