SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Function plus (children 1)
     ExpressionList (children 2)
      Identifier Y.dummy
      Literal UInt64_1
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier system.one (alias X)
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      TableIdentifier system.one (alias Y)
     TableJoin (children 1)
      Function equals (children 1)
       ExpressionList (children 2)
        Identifier X.dummy
        Identifier Y.dummy
   Set