[cyphar]

That's not the correct plural rule in English, you'd want

    let plural = match cases.len() {
        0 | 2.. => "s",
        1 => "",
    };

or something (though to be fair the original code snippet also handled "0" incorrectly -- should be "cases.len() != 1").

[iudqnolq]

And also to be fair you probably don't want to be hardcoding English pluralization rules.

[rabidferret]

I used to maintain a library which actually tried to implement proper English pluralization rules. I can confirm you don't want to do that.