SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Function arrayFilter (children 1)
     ExpressionList (children 2)
      Function lambda (children 1)
       ExpressionList (children 2)
        Function tuple (children 1)
         ExpressionList (children 1)
          Identifier x
        Function notEmpty (children 1)
         ExpressionList (children 1)
          Function concat (children 1)
           ExpressionList (children 2)
            Identifier x
            Literal \'hello\'
      Literal Array_[\'\']
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier system.one
    TablesInSelectQueryElement (children 1)
     ArrayJoin (children 1)
      ExpressionList (children 2)
       Literal Array_[UInt64_0] (alias elem)
       Function arrayMap (alias unused) (children 1)
        ExpressionList (children 2)
         Function lambda (children 1)
          ExpressionList (children 2)
           Function tuple (children 1)
            ExpressionList (children 1)
             Identifier x
           Function concat (children 1)
            ExpressionList (children 2)
             Identifier x
             Literal \'hello\'
         Literal Array_[\'\']
   Function not (children 1)
    ExpressionList (children 1)
     Function ignore (children 1)
      ExpressionList (children 1)
       Identifier elem
