docs: def keyring_update(cid, **kwargs):
      """
      Downloads and saves public key(s).
  
      Downloads public key(s) from the TVM service for a given client id and saves in the storage
      for further usage.
      Note, that the cocaine-runtime automatically refreshes its keyring after this call.
      """
      ctx = Context(**kwargs)
      ctx.execute_action('keyring:update', **{
          'tvm': ctx.repo.create_secure_service('tvm'),
          'cid': cid,
      })