code: func (f *Function) Update(zip []byte) error {
  	f.Log.Info("updating function")
  
  	updated, err := f.Service.UpdateFunctionCode(&lambda.UpdateFunctionCodeInput{
  		FunctionName: &f.FunctionName,
  		Publish:      aws.Bool(true),
  		ZipFile:      zip,
  	})
  
  	if err != nil {
  		return err
  	}
  
  	if err := f.CreateOrUpdateAlias(f.Alias, *updated.Version); err != nil {
  		return err
  	}
  
  	f.Log.WithFields(log.Fields{
  		"version": *updated.Version,
  		"name":    f.FunctionName,
  	}).Info("function updated")
  
  	return f.cleanup()
  }
docs: // Update the function with the given `zip`.