SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 5)
   ExpressionList (children 2)
    Function concat (alias y) (children 1)
     ExpressionList (children 2)
      Literal \'t\'
      Identifier x
    Literal \'rue\' (alias x)
   ExpressionList (children 1)
    Literal UInt64_1
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier tab
   Function equals (children 1)
    ExpressionList (children 2)
     Identifier y
     Literal \'true\'
   Set
