SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 2)
    Identifier x
    Identifier y
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier tab
   Function equals (children 1)
    ExpressionList (children 2)
     Function plus (children 1)
      ExpressionList (children 2)
       Function plus (children 1)
        ExpressionList (children 2)
         Identifier x
         Identifier y
       Literal UInt64_1
     Literal UInt64_3
