--- mpfr.pyx.orig	2019-10-17 20:24:39.000000000 -0400
+++ mpfr.pyx	2019-10-17 20:25:43.000000000 -0400
@@ -1,3 +1,5 @@
+# cython: language_level 3
+
 # -*- coding: utf-8 -*-
 # cython: embedsignature = True