code: func NewFile(path string, r io.Reader) *File {
  	if r == nil {
  		r = &bytes.Buffer{}
  	}
  	if seek, ok := r.(io.Seeker); ok {
  		seek.Seek(0, 0)
  	}
  	abs := path
  	if !filepath.IsAbs(path) {
  		abs, _ = filepath.Abs(path)
  	}
  	return &File{
  		Reader:  r,
  		Path:    path,
  		AbsPath: abs,
  	}
  }
docs: // NewFile takes the name of the file you want to
  // write to and a reader to reader from