code: def decode_contents(self, contents, obj):
          
          obj.siblings = [self.decode_content(c, RiakContent(obj))
                          for c in contents]
          # Invoke sibling-resolution logic
          if len(obj.siblings) > 1 and obj.resolver is not None:
              obj.resolver(obj)
          return obj
docs: Decodes the list of siblings from the protobuf representation
          into the object.
  
          :param contents: a list of RpbContent messages
          :type contents: list
          :param obj: a RiakObject
          :type obj: RiakObject
          :rtype RiakObject