def test_1():
    assert changeXY("xxhixx") == "yyhiyy"
def test_9():
    assert changeXY("hihi") == "hihi"
def test_0():
    assert changeXY("codex") == "codey"
def test_7():
    assert changeXY("xxx") == "yyy"
def test_8():
    assert changeXY("yyhxyi") == "yyhyyi"
def test_6():
    assert changeXY("") == ""
def test_5():
    assert changeXY("x") == "y"
def test_4():
    assert changeXY("h") == "h"
def test_3():
    assert changeXY("hiy") == "hiy"
def test_2():
    assert changeXY("xhixhix") == "yhiyhiy"