protected QueryBase VisitMatchNone(MatchNoneNode node, ElasticQueryMapperState state)
 {
     return(new MatchNoneQuery());
 }
 protected virtual BaseQuery HandleMatchNone(MatchNoneNode node, ElasticSearchQueryMapperState state)
 {
     //TODO: does this actually work? not sure about the syntax...
     return(!Query.MatchAll());
     //return Query.Bool(descriptor => descriptor.MustNot(new[] { Query.MatchAll() }));
 }