List the agencies located someplace lead by Alex Chalk.
SELECT DISTINCT ?uri WHERE { ?x <http://dbpedia.org/ontology/leaderName> <http://dbpedia.org/resource/Alex_Chalk> . ?uri <http://dbpedia.org/ontology/location> ?x  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/GovernmentAgency>}
Alex_Chalk