pub fn detect(data: &[u8], filename: Option<&str>) -> ShellExpand description
Detect the history format from the bytes and an optional filename hint.
Content sniffing wins over the filename (a renamed file is still parseable):
a zsh : <epoch>:<elapsed>; line or a fish - cmd: record is unambiguous; a
bash #<epoch> timestamp line marks timestamped bash. Otherwise the filename
disambiguates PSReadLine vs plain bash; failing that, Unknown (plain lines).