base64
pub const URL_SAFE: Config = Config{char_set: CharacterSet::UrlSafe, pad: true, strip_whitespace: false, line_wrap: LineWrap::NoWrap,}
=
Config{char_set: CharacterSet::UrlSafe, pad: true, strip_whitespace: false, line_wrap: LineWrap::NoWrap,}
URL-safe character set with padding