```
clickhouse-client -q 'create table typed_nulls( str Nullable(String) ) Engine=Log'

clickhouse-client --param_n='\N' --query='insert into typed_nulls(str) values ( {n:Nullable(String)} )' --format=Vertical
Code: 456. DB::Exception: Query parameter `n` was not set

clickhouse-client --param_n='aa' --query='insert into typed_nulls(str) values ( {n:Nullable(String)} )' --format=Vertical
Code: 456. DB::Exception: Query parameter `n` was not set
```

See also https://github.com/ClickHouse/ClickHouse/commit/a58996817ff0f639686f4248ac0be43a000aac85
/cc @tavplubix 
#pragma once
#include <Core/Names.h>
#include <Parsers/IAST_fwd.h>
namespace DB
{
class ASTQueryParameter;
class ReplaceQueryParameterVisitor
{
public:
    ReplaceQueryParameterVisitor(const NameToNameMap & parameters)
        : query_parameters(parameters)
    {}
    void visit(ASTPtr & ast);
private:
    const NameToNameMap & query_parameters;
    const String & getParamValue(const String & name);
    void visitQueryParameter(ASTPtr & ast);
};
}