code: def describe_repositories(self, registry_id=None, repository_names=None):
          
          if repository_names:
              for repository_name in repository_names:
                  if repository_name not in self.repositories:
                      raise RepositoryNotFoundException(repository_name, registry_id or DEFAULT_REGISTRY_ID)
  
          repositories = []
          for repository in self.repositories.values():
              # If a registry_id was supplied, ensure this repository matches
              if registry_id:
                  if repository.registry_id != registry_id:
                      continue
              # If a list of repository names was supplied, esure this repository
              # is in that list
              if repository_names:
                  if repository.name not in repository_names:
                      continue
              repositories.append(repository.response_object)
          return repositories
docs: maxResults and nextToken not implemented