code: public function getListCustomersByEmail(string $customerEmail): array
      {
          $cacheKey = sprintf('zoho_customer_%s', md5($customerEmail));
          $hit = $this->getFromCache($cacheKey);
  
          if (false === $hit) {
              $response = $this->sendRequest('GET', sprintf('customers?email=%s', $customerEmail));
  
              $result = $this->processResponse($response);
  
              $customers = $result['customers'];
  
              $this->saveToCache($cacheKey, $customers);
  
              return $customers;
          }
  
          return $hit;
      }
docs: @param string $customerEmail
  
  @return array