Ctrl+\ sends ASCII 28 (File Separator) in legacy terminals. This is
commonly used as SIGQUIT in Unix.
Ctrl+] sends ASCII 29 (Group Separator) in legacy terminals. This is
commonly used as the telnet escape character.
Ctrl+_ sends ASCII 31 (Unit Separator) in legacy terminals. On US
keyboards, - and _ are on the same physical key, so this also functions
as an alias for Ctrl+-.
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