SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Function sum (alias b) (children 1)
     ExpressionList (children 1)
      Function if (children 1)
       ExpressionList (children 3)
        Function equals (children 1)
         ExpressionList (children 2)
          Identifier s
          Literal \'\'
        Identifier v
        Literal UInt64_0
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Function VALUES (children 1)
       ExpressionList (children 2)
        Literal \'v Nullable(Int64), s String\'
        Literal Tuple_(UInt64_1, \'x\')
