code: function (onDone) {
  
  	l_validateUID();
  	var uid = ++l_states['uid_count'];
  
  	l_states.sync(function (err) {
  		if (err) {
  			return onDone(err);
  		}
  		LOG.warn('uid generated: ' + uid);
  		onDone(null, uid);
  	});
  }
docs: generate a next unique ID for user TODO: use SR.DS for l_states instead