code: def update(self, scaling_group, name=None, cooldown=None,
              min_entities=None, max_entities=None, metadata=None):
          
          if not isinstance(scaling_group, ScalingGroup):
              scaling_group = self.get(scaling_group)
          uri = "/%s/%s/config" % (self.uri_base, scaling_group.id)
          if cooldown is None:
              cooldown = scaling_group.cooldown
          if min_entities is None:
              min_entities = scaling_group.min_entities
          if max_entities is None:
              max_entities = scaling_group.max_entities
          body = {"name": name or scaling_group.name,
                  "cooldown": cooldown,
                  "minEntities": min_entities,
                  "maxEntities": max_entities,
                  "metadata": metadata or scaling_group.metadata,
                  }
          resp, resp_body = self.api.method_put(uri, body=body)
          return None
docs: Updates an existing ScalingGroup. One or more of the attributes can
          be specified.
  
          NOTE: if you specify metadata, it will *replace* any existing metadata.
          If you want to add to it, you either need to pass the complete dict of
          metadata, or call the update_metadata() method.