code: func (s *UIServerAPI) Export(ctx context.Context, addr common.Address) (json.RawMessage, error) {
  	// Look up the wallet containing the requested signer
  	wallet, err := s.am.Find(accounts.Account{Address: addr})
  	if err != nil {
  		return nil, err
  	}
  	if wallet.URL().Scheme != keystore.KeyStoreScheme {
  		return nil, fmt.Errorf("Account is not a keystore-account")
  	}
  	return ioutil.ReadFile(wallet.URL().Path)
  }
docs: // Export returns encrypted private key associated with the given address in web3 keystore format.
  // Example
  // {"jsonrpc":"2.0","method":"clef_export","params":["0x19e7e376e7c213b7e7e7e46cc70a5dd086daff2a"], "id":4}