print statement fixes

convert the print statement to a WARN level log line or to a call to the print
function, depending on the context.

account_banking/struct.py

@@ -23,7 +23,7 @@
 Define a struct class which behaves like a dict, but allows using
 object.attr alongside object['attr'].
 '''
-
+from __future__ import print_function
 __all__ = ['struct']