code: private function documentOperations($operations)
      {
          if (null === $operations) {
              return null;
          }
  
          $result = array();
  
          foreach ($operations as $operation) {
              $statusCodes = array();
              foreach ($operation->getStatusCodes() as $code => $description) {
                  $statusCodes[] = array(
                      'code' => $code,
                      'description' => $description
                  );
              }
  
              $result[] = array(
                  '@id' => '_:' . $operation->getName(),
                  '@type' => $operation->getType() ?: 'hydra:Operation',
                  'method' => $operation->getMethod(),
                  'label' => ($operation->getTitle())
                      ?
                      : $operation->getDescription(),
                  'description' => (null === $operation->getTitle())
                      ? null
                      : $operation->getDescription(),
                  'expects' => $this->getTypeReferenceIri($operation->getExpects()),
                  'returns' => $this->getTypeReferenceIri($operation->getReturns()),
                  'statusCodes' => $statusCodes
              );
          }
  
          return $result;
      }
docs: Creates a JSON-LD serialization of the passed operations
  
  @param array|null $operations The operations
  
  @return array|null The JSON-LD serialization of the operations