adding missing numpy import in backend-tools

Federico Ariza · Federico Ariza · commit b597b6ea0ef3 · 2017-08-11T15:52:57.000-04:00
diff --git a/lib/matplotlib/backend_tools.py b/lib/matplotlib/backend_tools.py
@@ -19,6 +19,7 @@
 import six
 import time
 import warnings
+import numpy as np
 
 
 class Cursors(object):
