py: Implement builtin reversed() function.
reversed function now implemented, and works for tuple, list, str, bytes
and user objects with __len__ and __getitem__.
Renamed mp_builtin_len to mp_obj_len to make it publically available (eg
for reversed).
diff --git a/py/builtin.h b/py/builtin.h
index 425cfec..25edf32 100644
--- a/py/builtin.h
+++ b/py/builtin.h
@@ -26,6 +26,7 @@
mp_obj_t mp_builtin___import__(uint n_args, mp_obj_t *args);
mp_obj_t mp_builtin_open(uint n_args, const mp_obj_t *args);
+mp_obj_t mp_builtin_len(mp_obj_t o);
MP_DECLARE_CONST_FUN_OBJ(mp_builtin___build_class___obj);
MP_DECLARE_CONST_FUN_OBJ(mp_builtin___import___obj);