update collections iterable import (#950)

Author: wallacbe

openhtf/output/callbacks/__init__.py

@@ -20,14 +20,14 @@
 examples.
 """
 
-import collections
 import contextlib
 import shutil
 import tempfile
 
 from openhtf import util
 from openhtf.util import data
 import six
+from six.moves import collections_abc
 
 
 # TODO(wallacbe): Switch to util
@@ -116,7 +116,7 @@ def __call__(self, test_record):
       serialized_record = self.serialize_test_record(test_record)
       if isinstance(serialized_record, six.string_types):
         outfile.write(serialized_record)
-      elif isinstance(serialized_record, collections.Iterable):
+      elif isinstance(serialized_record, collections_abc.Iterable):
         for chunk in serialized_record:
           outfile.write(chunk)
       else: