SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Function arraySort (children 1)
     ExpressionList (children 1)
      Function topK (children 2)
       ExpressionList (children 1)
        Identifier description
       ExpressionList (children 1)
        Literal UInt64_3
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier agg_over_nullable