a = [1, 2, 3]
assert a[0] == 1
assert a[1..2] == [2, 3]

s = "abcd"
assert s[0] == "a"
assert s[1..2] == "bc"

b = bytes("abcd", "utf-8")
assert b[0] == 97
assert b[1..2] == bytes("bc", "utf-8")