SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 2)
    Identifier x
    Identifier a
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Subquery (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 1)
          ExpressionList (children 2)
           Function arrayJoin (alias x) (children 1)
            ExpressionList (children 1)
             Literal Array_[\'Hello\', \'Goodbye\']
           Literal Array_[UInt64_1, UInt64_2, UInt64_3] (alias arr)
    TablesInSelectQueryElement (children 1)
     ArrayJoin (children 1)
      ExpressionList