def _register_admin(admin_site, model, admin_class):
try:<EOL><INDENT>admin_site.register(model, admin_class)<EOL><DEDENT>except admin.sites.AlreadyRegistered:<EOL><INDENT>pass<EOL><DEDENT>
Register model in the admin, ignoring any previously registered models.
        Alternatively it could be used in the future to replace a previously 
        registered model.