Try this simple python script: print map(None, (1,2)) return printed in standalone python this should produce ['1','2'] but in zope-2.4.0b3 we get an error: Error Type: TypeError Error Value: loop over non-sequence a sneak at the code in lib/python/AccessControl/ZopeGuards.py, the error occured in function "guarded_map", the parameter "seqs" should receive "(1, 2)" but instead it received "((1,2),)". This bug is reported to the collector as No. 2382. Li Dongfeng