Test commands
> echo "Hello world" | zstd -o test.zst
> zstdcat test.zst
Hello world
> vim test.zst
GA<ENTER>Hello<ESC>:wq<ENTER>
> zstdcat test.zst
Hello world
Hello
> vim
iGoodbye<ESC>:w >> test.zst<ENTER>:q!<ENTER>
> zstdcat test.zst
Hello world
Hello
Goodbye
> vim
:help
gzip<ENTER>:q<ENTER>:q<ENTER>