code: public function registerCommands(array $commands, callable $handler)
      {
          foreach ($commands as $command) {
              $handler_id = "app.handler." . join('', array_slice(explode("\\", $command), -1));
              $this[$handler_id] = $handler;
          }
      }
docs: register command for our application
  @param array $commands
  @param callable $handler