public void println() {
        try {
            out.write(System.lineSeparator());
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
@Test
    void println() {
        out.println();
        out.println("Hello ");
        out.close();
        assertThat(bytes, bytes(equalTo(System.lineSeparator() + "Hello " + System.lineSeparator())));
    }