how to check for remaininging hours in heroku code example

Example: hours remaining heroku

$ heroku ps -a <app name>

650 free dyno hours (65%) used
350 hours remaining

=== web (Free): bundle exec puma -C config/puma.rb (1)
web.1: idle 2016/05/16 15:51:45 -0700 (~ 22h ago)