code: def from_api_repr(cls, resource):
          
          etag = resource.get("etag")
  
          if etag is not None:
              resource = resource.copy()
              resource["etag"] = base64.b64decode(etag.encode("ascii"))
  
          return super(Policy, cls).from_api_repr(resource)
docs: Factory: create a policy from a JSON resource.
  
          Overrides the base class version to store :attr:`etag` as bytes.
  
          Args:
              resource (dict): JSON policy resource returned by the
              ``getIamPolicy`` REST API.
  
          Returns:
              :class:`Policy`: the parsed policy