SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 2)
    Function toDecimal256OrDefault (alias x) (children 1)
     ExpressionList (children 3)
      Literal \'Hello\'
      Literal UInt64_3
      Function CAST (children 1)
       ExpressionList (children 2)
        Literal \'123.456\'
        Literal \'Decimal256(3)\'
    Function toTypeName (children 1)
     ExpressionList (children 1)
      Identifier x
