Nested accumulates

rule "Fairness standard deviation"
when
  accumulate (
    $c : candidate
	  accumulate ( 
		  $f : FederalState ( winningCandidate == $c );
		  $candidateSum : sum( $f.getElectoralVotes() )
	  );
    $variance : sum($candidateSum * $candidateSum)
  )
then
  // Square root of variance is standard deviation
  scoreHolder.addSoftConstraintMatch(kcontext, Math.sqrt($variance));
end