docs: def change_object_content_type(self, container, obj, new_ctype,
              guess=False, extra_info=None):
          """
          Copies object to itself, but applies a new content-type. The guess
          feature requires the container to be CDN-enabled. If not then the
          content-type must be supplied. If using guess with a CDN-enabled
          container, new_ctype can be set to None. Failure during the put will
          result in a swift exception.
  
          The 'extra_info' parameter is included for backwards compatibility. It
          is no longer used at all, and will not be modified with swiftclient
          info, since swiftclient is not used any more.
          """
          return self._manager.change_object_content_type(container, obj,
                  new_ctype, guess=guess)