code: public function getPlan(string $planCode): array
      {
          $cacheKey = sprintf('plan_%s', $planCode);
          $hit = $this->getFromCache($cacheKey);
  
          if (false === $hit) {
              $response = $this->sendRequest('GET', sprintf('plans/%s', $planCode));
  
              $data = $this->processResponse($response);
              $plan = $data['plan'];
  
              $this->saveToCache($cacheKey, $plan);
  
              return $plan;
          }
  
          return $hit;
      }
docs: Returns a Plan by its identifier.
  
  @param string $planCode
  
  @throws \Exception
  
  @return array