Add explicit test for recarray format descriptors
diff --git a/example/example20.py b/example/example20.py
index 83725b5..83a914c 100644
--- a/example/example20.py
+++ b/example/example20.py
@@ -2,12 +2,16 @@
 from __future__ import print_function
 
 import numpy as np
-from example import create_rec_simple, create_rec_packed, create_rec_nested
+from example import (
+    create_rec_simple, create_rec_packed, create_rec_nested, print_format_descriptors
+)
 
 
 def check_eq(arr, data, dtype):
     np.testing.assert_equal(arr, np.array(data, dtype=dtype))
 
+print_format_descriptors()
+
 simple_dtype = np.dtype({'names': ['x', 'y', 'z'],
                          'formats': ['?', 'u4', 'f4'],
                          'offsets': [0, 4, 8]})