That Python example is broken in all kinds of ways, and is overly verbose. I would go with something like the following, which does spark some joy in me:

    matches = {l for l in open("beef.txt") if "lasagna" in l}
    print(*sorted(matches, reverse=True), sep="")

On And on the same note, the shell command is weird too, and should probably be:

    grep "lasagna" beef.txt | sort -nur

So the shell command is still definitely simpler for this case, but for anything more complex, I'd go with Python.

EDIT: I put back the `n` flag, in case the lines start with numbers.