DescribeQuery (children 1)
 TableExpression (children 1)
  Subquery (children 1)
   SelectWithUnionQuery (children 1)
    ExpressionList (children 1)
     SelectQuery (children 2)
      ExpressionList (children 4)
       Function plus (children 1)
        ExpressionList (children 2)
         Identifier test_table.id (alias a)
         Identifier test_table.id
       Function plus (children 1)
        ExpressionList (children 2)
         Identifier id
         Identifier id (alias b)
       Function plus (children 1)
        ExpressionList (children 2)
         Identifier b
         Identifier b
       Function plus (children 1)
        ExpressionList (children 2)
         Identifier test_table.id
         Identifier test_table.id
      TablesInSelectQuery (children 1)
       TablesInSelectQueryElement (children 1)
        TableExpression (children 1)
         TableIdentifier test_table