/**
  * @param Currency $currency
  *
  * @return mixed
  */
 private function fetchRate(Currency $currency)
 {
     return $this->rates->fetch($currency->market_id);
 }
 /**
  * @return mixed
  */
 public function fetchRate()
 {
     $id = Config::get('altwallets::calculation.btc_market_id');
     return $this->rates->fetch(2);
 }