code: func (c *CredentialsClient) HostCredentials(ctx context.Context, req auth.RegisterUsingTokenRequest) (*auth.PackedKeys, error) {
  	resp, err := c.clt.PostJSON(ctx, c.clt.Endpoint("webapi", "host", "credentials"), req)
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  
  	var packedKeys *auth.PackedKeys
  	err = json.Unmarshal(resp.Bytes(), &packedKeys)
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  
  	return packedKeys, nil
  }
docs: // HostCredentials is used to fetch host credentials for a node.