PREFIX wikibase: <http://wikiba.se/ontology#>
PREFIX wdt: <http://www.wikidata.org/prop/direct/>
PREFIX wd: <http://www.wikidata.org/entity/>
PREFIX bd: <http://www.bigdata.com/rdf#>
#item with (ambassador of x) or (ambassador of y) as P279
#(probably instead of P31)
SELECT distinct ?item ?itemLabel ?class ?classLabel where{
  {?class wdt:wdt:P31 wd:Q29918328 .} union {?class wdt:P31 wd:Q29918335}
  ?item wdt:P279 ?class.
SERVICE wikibase:label { bd:serviceParam wikibase:language "fr,en" }
FILTER  NOT EXISTS { # know exceptions
    {?item wdt:P279 wd:Q30064715 }
    union
    {?item wdt:P279 wd:Q110620461 }
  }
}

graph TD classDef projected fill:lightgreen; classDef literal fill:orange; classDef iri fill:yellow; v2("?class"):::projected v1("?item"):::projected c9(["bd:serviceParam"]):::iri c5(["wd:Q29918328"]):::iri c11(["fr,en"]):::literal c2(["wd:Q30064715"]):::iri c3(["wd:Q110620461"]):::iri c7(["wd:Q29918335"]):::iri f0[["not "]] subgraph f0e0["Exists Clause"] subgraph unione00[" Union "] subgraph unione00l[" "] style unione00l fill:#abf,stroke-dasharray: 3 3; e0v1 --"wdt:P279"--> e0c3 end subgraph unione00r[" "] style unione00r fill:#abf,stroke-dasharray: 3 3; e0v1 --"wdt:P279"--> e0c2 end unione00r <== or ==> unione00l end e0v1("?item"):::projected e0c2(["wd:Q30064715"]):::iri e0c3(["wd:Q110620461"]):::iri end f0--EXISTS--> f0e0 f0 --> v1 f0 --> c1 f0 --> c2 f0 --> c3 subgraph union0[" Union "] subgraph union0l[" "] style union0l fill:#abf,stroke-dasharray: 3 3; v1 --"wdt:P279"--> c3 end subgraph union0r[" "] style union0r fill:#abf,stroke-dasharray: 3 3; v1 --"wdt:P279"--> c2 end union0r <== or ==> union0l end subgraph union1[" Union "] subgraph union1l[" "] style union1l fill:#abf,stroke-dasharray: 3 3; v2 --"wdt:P31"--> c7 end subgraph union1r[" "] style union1r fill:#abf,stroke-dasharray: 3 3; v2 --"wdt:wdt:P31"--> c5 end union1r <== or ==> union1l end v1 --"wdt:P279"--> v2 subgraph s1["http://wikiba.se/ontology#label"] style s1 stroke-width:4px; c9 --"wikibase:language"--> c11 end