def test_slice_bounds(s):
assert s[0:100] == s
assert s[0:-100] == ''
assert s[100:1] == ''
def expect_index_error(s, index):
try:
s[index]
except IndexError:
pass
else:
assert False
unicode_str = "∀∂"
assert unicode_str[0] == "∀"
assert unicode_str[1] == "∂"
assert unicode_str[-1] == "∂"
test_slice_bounds(unicode_str)
expect_index_error(unicode_str, 100)
expect_index_error(unicode_str, -100)
ascii_str = "hello world"
test_slice_bounds(ascii_str)
assert ascii_str[0] == "h"
assert ascii_str[1] == "e"
assert ascii_str[-1] == "d"