code: func (w *HTTPProvider) Present(domain, token, keyAuth string) error {
  	var err error
  
  	challengeFilePath := filepath.Join(w.path, http01.ChallengePath(token))
  	err = os.MkdirAll(filepath.Dir(challengeFilePath), 0755)
  	if err != nil {
  		return fmt.Errorf("could not create required directories in webroot for HTTP challenge -> %v", err)
  	}
  
  	err = ioutil.WriteFile(challengeFilePath, []byte(keyAuth), 0644)
  	if err != nil {
  		return fmt.Errorf("could not write file in webroot for HTTP challenge -> %v", err)
  	}
  
  	return nil
  }
docs: // Present makes the token available at `HTTP01ChallengePath(token)` by creating a file in the given webroot path