SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Asterisk
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier enums
   Function in (children 1)
    ExpressionList (children 2)
     Identifier e
     Literal Tuple_(\'a\', \'d\')