public function set( $args, $assoc_args ) {
		list( $key, $value, $group, $expiration ) = $args;
		$result = wp_cache_set( $key, $value, $group, $expiration );

		if ( false === $result ) {
			WP_CLI::error( "Could not add object '$key' in group '$group'." );
		}

		WP_CLI::success( "Set object '$key' in group '$group'." );
	}