lr := io.LimitReader(r, 4)

	if _, err := io.Copy(os.Stdout, lr); err != nil {
		log.Fatal(err)
	}

	// Output:
	// some
}

func ExampleMultiReader() {
	r1 := strings.NewReader("first reader ")
	r2 := strings.NewReader("second reader ")
	r3 := strings.NewReader("third reader\n")
	r := io.MultiReader(r1, r2, r3)