Helper method to create options from list, or instance.

        Applies preprocess method if available to create a uniform
        output

def _create_options(self, items):
        """Helper method to create options from list, or instance.

        Applies preprocess method if available to create a uniform
        output
        """
        return OrderedDict(map(lambda x: (x.name, x),
                           coerce_to_list(items, self.preprocess)))