It is probably worth saying that all classes are of the new style - inheriting directly or indirectly from the standard "object". We need to state the expected type of the input arguments class SagaException the init method should allow no object to be specified: __init__ (self, message, object = None) class Url looks more complex than it is. It has a constructor which takes a string, a translate method and a bunch of properties. I am not sure that the string value should be available as a property because the string changes value any time that scheme, host etc. are modified and vice versa. What exactly does a line such as: scheme = property (get_scheme, set_scheme ) mean? class Context GFD90 does not mention the close() method. Is this here because you need some kind of destructor for a context? Now for the last page sd and isn as python takes named parameters we should have all parameters defaulting where reasonable def __init__ (self, url = None, session=None) : pass # None def list_services (self, service_filter = None, data_filter = None, authz_filter=None) : pass # [ServiceDescription] and for the ISN def __init__ (self, model, name, filter = None, url=None, session=None) : pass # None Steve