anchor.diff:  
   The RETURN clause
   
  -.[[Q7]]Q7
  +.[[Q6]]Q6
   [source, cypher]
   ----
   RETURN a AS a, (b - b) + SUM(c) AS foo
  
positive.code: ====
  By the grouping and aggregation semantics, the RETURN clause
  
  .[[Q6]]Q6
  [source, cypher]
  ----
  RETURN a AS a, b + SUM(c) * 2 AS foo
  
negative.code: 
  For instance, SQL does so by requiring users to list all grouping key expressions in the GROUP BY clause.
  If the GROUP BY clause is present in a query, the projection in the SELECT clause have to fulfill a similar syntax restriction as defined by this CIP.
  The SQL-equivalent of <<Q5>>
  
  [source, sql]
  ----
  