Function decode 

pub fn decode(b64_string: impl Into<String>) -> Result<Vec<u8>, BigIntError>

Decode a base64 string into an array of bytes.

Note: probably slower than using a standalone library to perform this conversion. However, again, it’s very neat c:

use big_int::base64::*;

assert_eq!(decode("SGVsbG8gd29ybGQh").unwrap(), b"Hello world!");