The original, which use `len` to calculate the line length, cause multibyte characters, (such as UTF-8 characters outside the ASCII range) to count as 2 characters or more. And thus visually, the lines look shorter than expected after formatting.
Compare, (`tw = 79`)
New formatting
```
It was in July, 1805, and the speaker was the well-known Anna Pávlovna Schérer,
maid of honor and favorite of the Empress Márya Fëdorovna. With these words she
greeted Prince Vasíli Kurágin, a man of high rank and importance, who was the
first to arrive at her reception. Anna Pávlovna had had a cough for some days.
She was, as she said, suffering from \emph{la grippe;} \emph{grippe} being then
a new word in St.~Petersburg, used only by the elite.
```
Old formatting
```
It was in July, 1805, and the speaker was the well-known Anna Pávlovna
Schérer, maid of honor and favorite of the Empress Márya Fëdorovna. With these
words she greeted Prince Vasíli Kurágin, a man of high rank and importance, who
was the first to arrive at her reception. Anna Pávlovna had had a cough for
some days. She was, as she said, suffering from \emph{la grippe;} \emph{grippe}
being then a new word in St.~Petersburg, used only by the elite.
```
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