public Printed<K, V> withLabel(final String label) {
        Objects.requireNonNull(label, "label can't be null");
        this.label = label;
        return this;
    }
@Test
    public void shouldThrowNullPointerExceptionIfLabelIsNull() {
        assertThrows(NullPointerException.class, () -> sysOutPrinter.withLabel(null));
    }