def test_remove_adjacent_different_types():
assert remove_adjacent([1, [], [], [[]], []]) == [1, [], [[]], []]
def test_remove_adjacent_empty_list():
assert remove_adjacent([]) == []
def test_remove_adjacent_all_equal():
assert remove_adjacent([1, 1, 1, 1]) == [1]
def test_remove_adjacent_all_unique():
assert remove_adjacent([1, 2, 3]) == [1, 2, 3]
def test_remove_adjacent():
assert remove_adjacent([1, 2, 2, 3]) == [1, 2, 3]