assert_se(utf8_is_printable("ascii is valid\tunicode", 22));
assert_se(utf8_is_printable("\342\204\242", 3));
assert_se(!utf8_is_printable("\341\204", 2));
assert_se(utf8_is_printable("ascii is valid\tunicode", 22));
assert_se(utf8_is_printable("\342\204\242", 3));
assert_se(!utf8_is_printable("\341\204", 2));