Index: Objects/rangeobject.c
===================================================================
--- Objects/rangeobject.c	(revision 56666)
+++ Objects/rangeobject.c	(working copy)
@@ -129,12 +129,31 @@
 	return rtn;
 }
 
+static int
+range_contains(rangeobject *r, PyIntObject *key) {
+    if (PyInt_Check(key)) {
+        int keyval = key->ob_ival;
+        int start = r->start;
+        int step = r->step;
+        int end = start + (r->len * step);
+
+        if ((step < 0 && keyval <= start && keyval > end) \
+           || (step > 0 && keyval >= start && keyval < end)) {
+            return ((keyval - start) % step) == 0;
+        }
+    }
+    return 0;
+}
+
 static PySequenceMethods range_as_sequence = {
 	(lenfunc)range_length,	/* sq_length */
 	0,			/* sq_concat */
 	0,			/* sq_repeat */
 	(ssizeargfunc)range_item, /* sq_item */
 	0,			/* sq_slice */
+    0, /* sq_ass_item */
+    0, /* sq_ass_slice */
+    (objobjproc)range_contains, /* sq_contains */
 };
 
 static PyObject * range_iter(PyObject *seq);