public function is_uploaded_file( $file_url ) {

        // Set default return value.
        $is_uploaded_file = false;

        // Get WordPress upload directory information.
        $wp_upload_directory = wp_upload_dir();

        // Check if the WordPress upload directory url matches the file url.
        if ( false !== strpos( $file_url, $wp_upload_directory[ 'baseurl' ] ) ) {

            // We now know the file is one that was uploaded to WordPress.
            $is_uploaded_file = true;

        }

        return $is_uploaded_file;

    }