code: public function checkInItem($item_id)
  	{
  		$request = new CheckInRequest($this->connector->agency_id, $item_id);
  		$this->emit('request.checkin', array($item_id));
  		$response = $this->post($request);
  		return new CheckInResponse($response);
  	}
docs: Check in an item
  
  @param  string  $item_id
  @return CheckInResponse