Goal: For given function type `Fn`, and any type `A` (any in this context means we don't restrict the type, and I don't have in mind any type) create a generic type which will take `Fn` as the first argument, `A` as the second, and will produce function type `G` which will be the same as `Fn` but with appended argument `A` as a last one. For example: Source challenge: https://github.com/type-challenges/type-challenges/tree/main/questions/00191-medium-append-argument Reference explanation: https://github.com/ghaiklor/type-challenges-solutions/blob/main/en/medium-append-argument.md