code: protected ImmutableList<Variable> prioritizeVariables(IntermediateQuery query, JoinLikeNode joinLikeNode) {
  
          /*
           * Sequential (order matters)
           */
          return extractAncestors(query, joinLikeNode).stream()
                  .sequential()
                  .flatMap(p -> extractPriorityVariables(query, p.parent, p.position))
                  .distinct()
                  .collect(ImmutableCollectors.toList());
      }
docs: TODO: implement seriously