def test_change_starting_index(self):
s = Span(1, 10, 10, index=1)
assert s.a == 1
assert s.b == 10
assert s.c == 10
assert s.index == 1
assert len(s) == 9
s2 = s.reindex(0)
assert s2.a == 0
assert s2.b == 9
assert s2.c == 9
assert s2.index == 0
assert len(s) == 9
s2 = s.reindex(-5)
assert s2.a == 0 - 5
assert s2.b == 9 - 5
assert s2.c == 9 - 5
assert s2.index == -5
assert len(s) == 9