code: func (r *reader) Read(b []byte) (int, error) {
  	r.Do(term.ClearAll)
  	n, err := r.ReadCloser.Read(b)
  	r.written += n
  	r.p.ValueInt(r.written)
  	r.render(term.CenterLine(r.p.String()))
  	return n, err
  }
docs: // Read implementation.