SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Function divide (children 1)
     ExpressionList (children 2)
      Function plus (children 1)
       ExpressionList (children 2)
        Function sum (children 1)
         ExpressionList (children 1)
          Identifier a
        Function sum (children 1)
         ExpressionList (children 1)
          Identifier b
      Function nullIf (children 1)
       ExpressionList (children 2)
        Function plus (children 1)
         ExpressionList (children 2)
          Function sum (children 1)
           ExpressionList (children 1)
            Identifier c
          Function sum (children 1)
           ExpressionList (children 1)
            Identifier d
        Literal UInt64_0
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier foo
