Error: template instance does not match template declaration

[Vitalii]

On Wednesday, 17 November 2021 at 18:00:59 UTC, Steven 
Schveighoffer wrote:
> On 11/17/21 7:55 AM, Vitalii wrote:
>> [...]
>
> Template parameters are of 3 types:
>
> 1. A type parameter. This has a single symbol name, and 
> represents a type *provided by the caller*.
>
> [...]

Steve, thank you very much for the detailed answer! Much has 
become clearer.