Implement repr.
diff --git a/py/builtin.h b/py/builtin.h
index 3401528..cb8836c 100644
--- a/py/builtin.h
+++ b/py/builtin.h
@@ -21,5 +21,6 @@
 MP_DECLARE_CONST_FUN_OBJ(mp_builtin_pow_obj);
 MP_DECLARE_CONST_FUN_OBJ(mp_builtin_print_obj);
 MP_DECLARE_CONST_FUN_OBJ(mp_builtin_range_obj);
+MP_DECLARE_CONST_FUN_OBJ(mp_builtin_repr_obj);
 MP_DECLARE_CONST_FUN_OBJ(mp_builtin_sorted_obj);
 MP_DECLARE_CONST_FUN_OBJ(mp_builtin_sum_obj);