Make bin() implementation parallel oct() and hex() so that int/long subclasses can override or so that other classes can support.
diff --git a/Objects/intobject.c b/Objects/intobject.c
index f98aee0..5210ee8 100644
--- a/Objects/intobject.c
+++ b/Objects/intobject.c
@@ -934,6 +934,12 @@
 }
 
 static PyObject *
+int_bin(PyObject *v)
+{
+        return PyNumber_ToBase(v, 2);
+}
+
+static PyObject *
 int_oct(PyIntObject *v)
 {
 	return _PyInt_Format(v, 8, 0);
@@ -1231,6 +1237,7 @@
 	0,			/* nb_inplace_floor_divide */
 	0,			/* nb_inplace_true_divide */
 	(unaryfunc)int_int,	/* nb_index */
+	(unaryfunc)int_bin, 	/* nb_bin */
 };
 
 PyTypeObject PyInt_Type = {
diff --git a/Objects/longobject.c b/Objects/longobject.c
index c65d0c0..b603dda 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -3301,6 +3301,12 @@
 }
 
 static PyObject *
+long_bin(PyObject *v)
+{
+        return PyNumber_ToBase(v, 2);
+}
+
+static PyObject *
 long_oct(PyObject *v)
 {
 	return _PyLong_Format(v, 8, 1, 0);
@@ -3540,6 +3546,7 @@
 	0,				/* nb_inplace_floor_divide */
 	0,				/* nb_inplace_true_divide */
 	long_long,			/* nb_index */
+	long_bin,			/* nb_bin */
 };
 
 PyTypeObject PyLong_Type = {
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index e0ae55b..093fd20 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -3743,6 +3743,7 @@
 		if (base->tp_flags & Py_TPFLAGS_HAVE_INDEX) {
 			COPYNUM(nb_index);
 		}
+		COPYNUM(nb_hex);
 	}
 
 	if (type->tp_as_sequence != NULL && base->tp_as_sequence != NULL) {
@@ -5135,6 +5136,7 @@
 SLOT0(slot_nb_int, "__int__")
 SLOT0(slot_nb_long, "__long__")
 SLOT0(slot_nb_float, "__float__")
+SLOT0(slot_nb_bin, "__bin__")
 SLOT0(slot_nb_oct, "__oct__")
 SLOT0(slot_nb_hex, "__hex__")
 SLOT1(slot_nb_inplace_add, "__iadd__", PyObject *, "O")
@@ -5802,6 +5804,8 @@
 	       "long(x)"),
 	UNSLOT("__float__", nb_float, slot_nb_float, wrap_unaryfunc,
 	       "float(x)"),
+	UNSLOT("__bin__", nb_bin, slot_nb_bin, wrap_unaryfunc,
+	       "bin(x)"),
 	UNSLOT("__oct__", nb_oct, slot_nb_oct, wrap_unaryfunc,
 	       "oct(x)"),
 	UNSLOT("__hex__", nb_hex, slot_nb_hex, wrap_unaryfunc,