function onCommand( cmd, success ) {
		self._count += 1;
		debug( 'Command count: %d', self._count );

		// Update the internal command history buffer: [..., <id>, <cmd>, <success>, ...]
		self._history.push( self._count, cmd, success );

		// TODO: if successful and if necessary, (asynchronously?) write the command to a history file (question: do we only want to write successful commands to the history file? maybe we need to option for limiting to successful commands?)

		// TODO: if necessary, (asynchronously?) write the command and result to a log file (JSON serialization?)
	}
Callback invoked upon executing a command.

@private
@param {string} cmd - command
@param {boolean} success - boolean indicating whether the command successfully executed