How to make num +1?

[Pony-CW]

全文皆由中文机器翻译而来，如果有语法问题恕我无能为力
The entire text is machine translated from Chinese, so I can't help if there are grammatical problems.

I wanted to download a Pixiv post with multiple images, but didn't like the fact that the num starts at 0, so thought about how to make it +1
But... I don't know python and I can't write python arbitrary expressions (I don't understand all the functions), so I'm looking for help from programmers on how to write it so that it's +1 correctly!

Here is my configuration

...
    "pixiv": {
      "directory": [
        "Pixiv"
      ],
      "filename": {
        "len((caption+'#'+(' #'.join(tags))+title).encode()) > 160 and page_count == 1": "Pixiv-{user[name]}-{date:%Y_%m_%d}_UTC0-{title}-#{tags:J #}-{caption[b0:100]!H:?//}..._{id}.{extension}",
        "len((caption+'#'+(' #'.join(tags))+title).encode()) < 160 and page_count == 1": "Pixiv-{user[name]}-{date:%Y_%m_%d}_UTC0-{title}-#{tags:J #}{caption!H:?//}_{id}.{extension}",
        "len((caption+'#'+(' #'.join(tags))+title).encode()) > 160": "Pixiv-{user[name]}-{date:%Y_%m_%d}_UTC0-{title}-#{tags:J #}_{caption[b0:100]!H:?//}_{id}-{num+1}.{extension}",
        "len((caption+'#'+(' #'.join(tags))+title).encode()) < 160": "Pixiv-{user[name]}-{date:%Y_%m_%d}_UTC0-{title}-#{tags:J #}-{caption!H:?//}_{id}-{num+1}.{extension}"
      },
      "refresh-token": "xxxxxxxxxxxx"
    },
...

I know, I know, {num+1} is stupid.

[mikf]

I've added an A format specifier (78ae0ba),
so you'll be able to do {num:A+1} in the next release.

[Pony-CW]

Thanks!😊