code: public function getInvoice(string $invoiceId)
      {
          $cacheKey = sprintf('zoho_invoice_%s', $invoiceId);
          $hit = $this->getFromCache($cacheKey);
  
          if (false === $hit) {
              $response = $this->sendRequest('GET', sprintf('invoices/%s', $invoiceId));
  
              $result = $this->processResponse($response);
  
              $invoice = $result['invoice'];
  
              $this->saveToCache($cacheKey, $invoice);
  
              return $invoice;
          }
  
          return $hit;
      }
docs: @param string $invoiceId The invoice's id
  
  @throws \Exception
  
  @return array