code: func (ns *Namespace) Ext(path interface{}) (string, error) {
  	spath, err := cast.ToStringE(path)
  	if err != nil {
  		return "", err
  	}
  	spath = filepath.ToSlash(spath)
  	return _path.Ext(spath), nil
  }
docs: // Ext returns the file name extension used by path.
  // The extension is the suffix beginning at the final dot
  // in the final slash-separated element of path;
  // it is empty if there is no dot.
  // The input path is passed into filepath.ToSlash converting any Windows slashes
  // to forward slashes.