anchor.diff:              | CreateRelationCall _ -> Choice1Of2 (executeCreate cypher next)
               | DeleteNodeCall _
               | DeleteRelationshipCall _ -> Choice1Of2 (executeDelete cypher next)
  +            | MergeRelationCall _ -> Choice1Of2 (executeMerge cypher next)
               | _ -> unexpectedExpr context next
           let context = "After WHERE expression"
               
  
positive.code:         | DeleteRelationshipCall(Var(rel)) ->
              printfn "Delete relationship: %s (type: %s)" rel.Name rel.Type.Name
              cypher.Delete(rel.Name)
          | _ -> unsupportedScenario "Delete node" deleteExpr
  
      let private executeWhere<'T> (cypher: ICypherFluentQuery) (whereExpr: Expr): InterpreterResult<'T> =
          let executeNextExpr context cypher next =
  
negative.code:         | LeftRel of leftNode:NodeExpr * rel:RelExpr * rightNode:NodeExpr * isUnique:bool
          | RightRel of leftNode:NodeExpr * rel:RelExpr * rightNode:NodeExpr * isUnique:bool
          | LeftOrRightRel of leftNode:NodeExpr * rel:RelExpr * rightNode:NodeExpr
          member x.CypherExprForCreate =
              match x with
              | LeftRel(lnode,rel,rnode,_) ->
                  sprintf "%s<-%s-%s" lnode.CypherExpr rel.CypherExpr rnode.CypherExpr
  