+usage () {
+ echo >&2 "usage: $(basename $0)"' [<branchname> [start-point]]
+
+If no arguments, show available branches and mark current branch with a star.
+If one argument, create a new branch <branchname> based off of current HEAD.
+If two arguments, create a new branch <branchname> based off of <start-point>.
+'
+ exit 1
+}
+