def test_empty_crunch():
assert crunch([]) == ""
def test_single_item_crunch():
assert crunch([77]) == "77:0"
def test_advanced():
assert crunch([50, 50, 3, 50, 50, 3, 60, 70,
70]) == "50:0-1,3-4;3:2,5;60:6;70:7-8"
def test_basic_crunch():
assert crunch([1, 2, 3]) == "1:0;2:1;3:2"
def test_order():
assert crunch([2, 1]) == "2:0;1:1"
def test_basic_broken_run():
assert crunch([1, 2, 1]) == "1:0,2;2:1"
def test_basic_run():
assert crunch([1, 1, 1]) == "1:0-2"