code: func (b *Bittrex) CancelOrder(orderID string) (err error) {
  	r, err := b.client.do("GET", "market/cancel?uuid="+orderID, "", true)
  	if err != nil {
  		return
  	}
  	var response jsonResponse
  	if err = json.Unmarshal(r, &response); err != nil {
  		return
  	}
  	err = handleErr(response)
  	return
  }
docs: // CancelOrder is used to cancel a buy or sell order.