From 4bed228adba88f9c5b85eaad308582db79a95b7b Mon Sep 17 00:00:00 2001
From: Eric Wieser <wieser.eric@gmail.com>
Date: Sun, 8 Jul 2018 17:38:33 +0100
Subject: MAINT: Restore previous behavior on subclasses

---
 numpy/core/numeric.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'numpy/core/numeric.py')

diff --git a/numpy/core/numeric.py b/numpy/core/numeric.py
index a9fa3efe0..e5570791a 100644
--- a/numpy/core/numeric.py
+++ b/numpy/core/numeric.py
@@ -1509,8 +1509,8 @@ def normalize_axis_tuple(axis, ndim, argname=None, allow_duplicate=False):
     --------
     normalize_axis_index : normalizing a single scalar axis
     """
-    # Speed-up most common cases.
-    if not isinstance(axis, (list, tuple)):
+    # Optimization to speed-up the most common cases.
+    if type(axis) not in (tuple, list):
         try:
             axis = [operator.index(axis)]
         except TypeError:
-- 
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