BASE64 implement in Rust.
```rust extern crate base64easy; use base64easy::{encode, decode};
let a = encode("abc".to_string());
let b = decode("YWJj".to_string());
```
```
cargo build -- example simple
$ ./simple e abc77
YWJjNzc=
$ ./simple d YWJjNzc=
abc77
```