Question: Give me all communist countries.
SPARQL query:
PREFIX onto: <http://dbpedia.org/ontology/>
PREFIX res: <http://dbpedia.org/resource/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT DISTINCT ?uri
WHERE {
        ?uri rdf:type onto:Country .
      { ?uri onto:governmentType res:Communism . }
        UNION
      { ?uri onto:governmentType res:Communist_state . }
}