You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mutator.go
    path of file: ./repos/gardener/pkg/provider-local/webhook/nodeagentosc
    
    the code of the file until where you have to start completion: // Copyright 2023 SAP SE or an SAP affiliate company. All rights reserved. This file is licensed under
    
func modifyFile(files []extensionsv1alpha1.File, path string, mutateFunc func(string) string) error {
	if file := extensionswebhook.FileWithPath(files, path); file != nil {
		oldContent, err := fciCodec.Decode(file.Content.Inline)
		if err != nil {
			return fmt.Errorf("failed to decode file %q: %w", path, err)
		}

		newContent := mutateFunc(string(oldContent))

		var newFileContent *extensionsv1alpha1.FileContentInline
		if newFileContent, err = fciCodec.Encode([]byte(newContent), file.Content.Inline.Encoding); err != nil {
			return fmt.Errorf("could not encode file: %q: %w", path, err)
		}
		*file.Content.Inline = *newFileContent
	}

	return nil
}