Add default imports

Author: DPeterK

lib/iris/experimental/representation.py

@@ -20,6 +20,9 @@
 
 """
 
+from __future__ import (absolute_import, division, print_function)
+from six.moves import (filter, input, map, range, zip)  # noqa
+
 
 class CubeRepresentation(object):
     """