Check if a string contains another string

In short: I appended the FLAC MD5 audio checksum to the Comment tag and now I'd like to be able to verify if they match, that is, if the Comment tag contains that exact MD5 value. (Useful for future conversions.)

I don't want to modify the files in any way, this is just for checking.
I found a somewhat similar problem with a neat solution here:

$if($eql(%artist%,%albumartist%),'ok','problem')

Is there a way to modify this, so that it doesn't check if the two columns are equal, but instead checks if one contains the other?

EDIT: Never mind, I think I got it.
$ifgreater($strstr(%comment%,%_md5audio%),0,yes,no)

It was even in the help examples, but for some reason it didn't work when I first tried it.
Let me know if there's a better solution, though.

Something similar has been discussed just 4 days ago: