code: func (c *Client) AppUpdate(appIdentity string, options *AppUpdateOpts, message string) (*App, error) {
  	rh := RequestHeaders{CommitMessage: message}
  	var appRes App
  	return &appRes, c.PatchWithHeaders(&appRes, "/apps/"+appIdentity, options, rh.Headers())
  }
docs: // Update an existing app.
  //
  // appIdentity is the unique identifier of the App. options is the struct of
  // optional parameters for this action.