def normalize(self):
        """
        Makes sure this egg distribution is stored only as an egg file.

        The egg file will be created from another existing distribution format
        if needed.

        """
        if self.has_egg_file():
            if self.has_zip():
                self.__remove_zip()
        else:
            if self.has_egg_folder():
                if not self.has_zip():
                    self.__zip_egg_folder()
                self.__remove_egg_folder()
            self.__rename_zip_to_egg()