query: PREFIX gas: <http://www.bigdata.com/rdf/gas#>
  SELECT (max(?depth)+1 as ?level) WHERE {
    SERVICE gas:service { gas:program gas:gasClass "com.bigdata.rdf.graph.analytics.SSSP" ;
      gas:in wd:Q2186582 ;
      gas:out ?item ;
      gas:out1 ?depth ;
      gas:linkType wdt:P2499 .
    }
  }