** out.  Or if the FILE arguments are omitted, show all unsaved changes
** currently in the working check-out.
**
** The default output format is a "unified patch" (the same as the
** output of "diff -u" on most unix systems).  Many alternative formats
** are available.  A few of the more useful alternatives:
**
**    --tk              Pop up a TCL/TK-based GUI to show the diff
**    --tk              Pop up a Tcl/Tk-based GUI to show the diff
**    --by              Show a side-by-side diff in the default web browser
**    -b                Show a linear diff in the default web browser
**    -y                Show a text side-by-side diff
**    --webpage         Format output as HTML
**    --webpage -y      HTML output in the side-by-side format
**
** The "--from VERSION" option is used to specify the source check-in

**   --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
**   --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
**   --json                      Output formatted as JSON
**   -N|--new-file               Alias for --verbose
**   --numstat                   Show only the number of added and deleted lines
**   -y|--side-by-side           Side-by-side diff
**   --strip-trailing-cr         Strip trailing CR
**   --tcl                       TCL-formated output used internally by --tk
**   --tclsh PATH                TCL/TK used for --tk (default: "tclsh")
**   --tcl                       Tcl-formated output used internally by --tk
**   --tclsh PATH                Tcl/Tk shell used for --tk (default: "tclsh")
**   --tk                        Launch a Tcl/Tk GUI for display
**   --to VERSION                Select VERSION as target for the diff
**   --undo                      Diff against the "undo" buffer
**   --unified                   Unified diff
**   -v|--verbose                Output complete text of added or deleted files
**   -h|--versions               Show compared versions in the diff header
**   --webpage                   Format output as a stand-alone HTML webpage