`git log -1 HEAD` but write `git log -1 HEAD --`; the former will not work
if you happen to have a file called `HEAD` in the work tree.
+ * many commands allow a long option "--option" to be abbreviated
+ only to their unique prefix (e.g. if there is no other option
+ whose name begins with "opt", you may be able to spell "--opt" to
+ invoke the "--option" flag), but you should fully spell them out
+ when writing your scripts; later versions of Git may introduce a
+ new option whose name shares the same prefix, e.g. "--optimize",
+ to make a short prefix that used to be unique no longer unique.
+
ENHANCED OPTION PARSER
----------------------