SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Function max (children 1)
     ExpressionList (children 1)
      Function length (children 1)
       ExpressionList (children 1)
        Function mapKeys (children 1)
         ExpressionList (children 1)
          Identifier a
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Subquery (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 3)
          ExpressionList (children 1)
           Identifier a
          TablesInSelectQuery (children 1)
           TablesInSelectQueryElement (children 1)
            TableExpression (children 1)
             Function generateRandom (children 1)
              ExpressionList (children 4)
               Literal \'a Map(String, String)\'
               Literal UInt64_20
               Literal UInt64_5
               Literal UInt64_20
          Literal UInt64_1000
