**                               as binary
**   --branch BRANCH             Show diff of all changes on BRANCH
**   --brief                     Show filenames only
**   -b|--browser                Show the diff output in a web-browser
**   --by                        Shorthand for "--browser -y"
**   -ci|--checkin VERSION       Show diff of all changes in VERSION
**   --command PROG              External diff program. Overrides "diff-command"
**   -c|--context N              Show N lines of context around each change, with
**                               negative N meaning show all content
**   --dark                      Use dark mode for the Tcl/Tk-based GUI and HTML
**   --diff-binary BOOL          Include binary files with external commands
**   --exec-abs-paths            Force absolute path names on external commands
**   --exec-rel-paths            Force relative path names on external commands
**   -r|--from VERSION           Select VERSION as source for the diff
**   -w|--ignore-all-space       Ignore white space when comparing lines
**   -i|--internal               Use internal diff logic