private function get_user_roles( $user_id = 0 ) {

		// Default return value
		$roles = array();

		// Bail if cannot query the user
		if ( ! class_exists( 'WP_User' ) || empty( $user_id ) ) {
			return false;
		}

		// User ID
		$user = new WP_User( $user_id );
		if ( isset( $user->roles ) ) {
			$roles = (array) $user->roles;
		}

		// Super admin
		if ( is_multisite() && is_super_admin( $user_id ) ) {
			$roles[] = 'super_admin';
		}

		return implode( ',', $roles );
	}