public void stringYak()
{
assertEquals("Input: stringYak(\"yakpak\")", "pak", exercises.StringYak("yakpak"));
assertEquals("Input: stringYak(\"pakyak\")", "pak", exercises.StringYak("pakyak"));
assertEquals("Input: stringYak(\"yak123ya\")", "123ya", exercises.StringYak("yak123ya"));
assertEquals("Input: stringYak(\"yak\")", "", exercises.StringYak("yak"));
assertEquals("Input: tringYak(\"yakxxxyak\")", "xxx", exercises.StringYak("yakxxxyak"));
assertEquals("Input: stringYak(\"HiyakHi\")", "HiHi", exercises.StringYak("HiyakHi"));
assertEquals("Input: stringYak(\"xxxyakyyyakzzz\")", "xxxyyzzz", exercises.StringYak("xxxyakyyyakzzz"));
}
