set +xv
. /t/prompt/prompt 
test -d demo && rm -rf demo/
test -d ../demo && cd .. && rm -rf demo/ 
clear
: ------------------------------------------------------------------------
mkdir demo
cd demo
git init
echo 'main() {puts("Hello World!");}' > hello.c
make hello && ./hello
git add hello.c
git commit -q -m "1st hello" 
git checkout -b universe;  git clean -f
echo 'main() {puts("Hello Universe!");}' > hello.c
git add hello.c
echo "// FIXME: includes" >> hello.c
git add hello.c
git commit -q -m "notes to self"
git checkout master
cat hello.c
echo 'main() {puts("Hello Universe!"); exit(0);}' > hello.c
git add hello.c
git commit -q -m "fixed exit code"
git merge universe
git cat-file -p universe:hello.c > hello.c
git add hello.c
git commit -q -m "merged"
cat hello.c
git checkout HEAD^
git checkout HEAD^
cat hello.c
git checkout master
sleep 2; echo "this emulates unsaved vim session" > .hello.c.swp 
git clean -f
: ------------------------------------------------------------------------
cd ..