Codice per http://lloc.it/visualizzare-dati-xml-con-wordpress.html

countryinfo.php

<?php

add_shortcode( 'countryinfo', function ( $atts ) {
	$params = shortcode_atts( [ 'lang' => 'de', 'country' => 'DE', 'username' => 'USERNAME' ], $atts );
	$url    = add_query_arg( $params, 'http://ws.geonames.org/countryInfo' );
	$result = wp_remote_get( $url );

	if ( is_wp_error( $result ) ) {
		return $result->get_error_message();
	}

	return $result['body'];
} );