SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function emptyArrayToSingle (alias arr) (children 1)
     ExpressionList (children 1)
      Function arrayMap (children 1)
       ExpressionList (children 2)
        Function lambda (children 1)
         ExpressionList (children 2)
          Function tuple (children 1)
           ExpressionList (children 1)
            Identifier x
          Function nullIf (children 1)
           ExpressionList (children 2)
            Identifier x
            Literal UInt64_2
        Function arrayJoin (children 1)
         ExpressionList (children 1)
          Function array (children 1)
           ExpressionList (children 3)
            Function emptyArrayUInt8 (children 1)
             ExpressionList
            Literal Array_[UInt64_1]
            Literal Array_[UInt64_2, UInt64_3]
