The answer depends on the version:in 2.5 "If the syntax "**expression" appears in the function call, "expression" must evaluate to a (subclass of) dictionary, " in 3.1 "If the syntax **expression appears in the function call, expression must evaluate to a mapping,"
ReferenceManual.Epressions.Primaries.Calls Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
