internal/bufio/bufio.go
func (w *Writer) WriteString(s string) {
	if w.err != nil {
		return
	}
	w.wr.WriteString(s)
}
func (w *Writer) WriteString(s string) {
	if w.err != nil {
		return
	}
	w.wr.WriteString(s)
}
// WriteString writes a string.