REF: https://deno.land/manual/examples/unix_cat
echo "hello world cat" > test.txt
deno run --allow-read cat.ts test.txt
# hello world cat
REF: https://deno.land/manual/examples/file_system_events
deno run --allow-read watcher.ts
# watch this directory
# Terminal1
$ deno run --allow-net --allow-read api.ts
# Terminal2
$ curl -X POST http://localhost:8000/todos
# > 880
### generate random id and file
$ cat 880.txt
This is todo itm.
ID is 880.