doTestTrimLeadingFrom("x-xx", "x-xx");
    doTestTrimLeadingFrom("x-x--xx---x----x", "x-x--xx---x----x");
    // additional testing using the doc example
    assertThat(anyOf("ab").trimLeadingFrom("abacatbab")).isEqualTo("catbab");
  }

  private void doTestTrimLeadingFrom(String in, String out) {
    // Try a few different matchers which all match '-' and not 'x'
    assertThat(is('-').trimLeadingFrom(in)).isEqualTo(out);