Looks for default values for unset attributes.  If
           class variable representing attribute is None, then
           it must be defined as an instance variable.

def __setAttributeDefaults(self):
        """Looks for default values for unset attributes.  If
           class variable representing attribute is None, then
           it must be defined as an instance variable.
        """
        for k,v in self.__class__.attributes.items():
            if v is not None and self.attributes.has_key(k) is False:
                if isinstance(v, types.FunctionType):
                    self.attributes[k] = v(self)
                else:
                    self.attributes[k] = v