PEP 227 implementation
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.
diff --git a/Include/cellobject.h b/Include/cellobject.h
new file mode 100644
index 0000000..cc4a159
--- /dev/null
+++ b/Include/cellobject.h
@@ -0,0 +1,28 @@
+/* Cell object interface */
+
+#ifndef Py_CELLOBJECT_H
+#define Py_CELLOBJECT_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct {
+ PyObject_VAR_HEAD
+ PyObject *ob_ref;
+} PyCellObject;
+
+extern DL_IMPORT(PyTypeObject) PyCell_Type;
+
+#define PyCell_Check(op) ((op)->ob_type == &PyCell_Type)
+
+extern DL_IMPORT(PyObject *) PyCell_New(PyObject *);
+extern DL_IMPORT(PyObject *) PyCell_Get(PyObject *);
+extern DL_IMPORT(int) PyCell_Set(PyObject *, PyObject *);
+
+#define PyCell_GET(op) (((PyCellObject *)(op))->ob_ref)
+#define PyCell_SET(op, v) (((PyCellObject *)(op))->ob_ref = v)
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_TUPLEOBJECT_H */