def _extract_constants(self, specification):
        """ Removes attributes and computes constants

        """
        constants = {}

        for attribute in specification.attributes:

            if attribute.allowed_choices and len(attribute.allowed_choices) > 0:

                name = attribute.local_name.upper()

                for choice in attribute.allowed_choices:
                    constants["CONST_%s_%s" % (name, choice.upper())] = choice

        return constants
Removes attributes and computes constants