SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Literal \'OK\' (alias s)
   ExpressionList (children 1)
    Asterisk
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Function param_test (children 1)
       ExpressionList (children 1)
        Function equals (children 1)
         ExpressionList (children 2)
          Identifier test_str
          Identifier s
