22.2.2

```sql
create table source (a UInt64, b UInt64, c String) Engine= Memory;

insert into source select number, number, 'attr-'||toString(number) from numbers(10);

CREATE DICTIONARY dict1
( a UInt64 , b UInt64  HIERARCHICAL, c String
) PRIMARY KEY a
SOURCE(clickhouse(DB 'default' TABLE 'source'))
LIFETIME(300) LAYOUT(flat());

SELECT dictGetDescendants('dict1', toUInt64(2), 0)
DB::Exception: Illegal type of third argument of function dictGetDescendants
Expected const unsigned integer.: While processing dictGetDescendants('dict1', toUInt64(2), 0). (ILLEGAL_TYPE_OF_ARGUMENT)

-- but !

SELECT dictGetDescendants('dict1', materialize(toUInt64(2)), 0)
┌─dictGetDescendants('dict1', materialize(toUInt64(2)), 0)─┐
│ [2]                                                      │
└──────────────────────────────────────────────────────────┘

SELECT dictGetDescendants('dict1', number, 0)
FROM numbers(3)
┌─dictGetDescendants('dict1', number, 0)─┐
│ [0]                                    │
│ [1]                                    │
│ [2]                                    │
└────────────────────────────────────────┘
```

> "DB::Exception: Illegal type of third argument of function dictGetDescendants"

Also the message is incorrect, the problem is in the second argument,  not the third argument 
#pragma once
#include <DataTypes/DataTypesNumber.h>
#include <DataTypes/DataTypesDecimal.h>
#include <DataTypes/DataTypeArray.h>
#include <DataTypes/DataTypeString.h>
#include <DataTypes/DataTypeDate.h>
#include <DataTypes/DataTypeDateTime.h>
#include <DataTypes/DataTypeTuple.h>
#include <DataTypes/DataTypeUUID.h>
#include <DataTypes/DataTypeNullable.h>
#include <DataTypes/DataTypeLowCardinality.h>
#include <Common/typeid_cast.h>
#include <Common/assert_cast.h>
#include <Columns/ColumnsNumber.h>
#include <Columns/ColumnConst.h>
#include <Columns/ColumnArray.h>
#include <Columns/ColumnString.h>
#include <Columns/ColumnTuple.h>
#include <Columns/ColumnNullable.h>
#include <Access/Common/AccessFlags.h>
#include <Interpreters/Context.h>