correct way of importing for newer python versions

processing/post/addCalculation.py

@@ -4,7 +4,7 @@ import os
 import sys
 from optparse import OptionParser
 import re
-import collections
+from collections.abc import Iterable
 import math                                                                                         # noqa
 
 import scipy                                                                                        # noqa
@@ -18,7 +18,7 @@ scriptName = os.path.splitext(os.path.basename(__file__))[0]
 scriptID   = ' '.join([scriptName,damask.version])
 
 def listify(x):
-  return x if isinstance(x, collections.Iterable) else [x]
+  return x if isinstance(x, Iterable) else [x]
 
 
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