code: def set_metadata(self, container, metadata, clear=False, prefix=None):
          
          # Add the metadata prefix, if needed.
          if prefix is None:
              prefix = CONTAINER_META_PREFIX
          massaged = _massage_metakeys(metadata, prefix)
          new_meta = {}
          if clear:
              curr_meta = self.api.get_container_metadata(container,
                      prefix=prefix)
              for ckey in curr_meta:
                  new_meta[ckey] = ""
          utils.case_insensitive_update(new_meta, massaged)
          name = utils.get_name(container)
          uri = "/%s" % name
          resp, resp_body = self.api.method_post(uri, headers=new_meta)
          return 200 <= resp.status_code <= 299
docs: Accepts a dictionary of metadata key/value pairs and updates the
          specified container metadata with them.
  
          If 'clear' is True, any existing metadata is deleted and only the
          passed metadata is retained. Otherwise, the values passed here update
          the container's metadata.
  
          By default, the standard container metadata prefix
          ('X-Container-Meta-') is prepended to the header name if it isn't
          present. For non-standard headers, you must include a non-None prefix,
          such as an empty string.