Can't deserialize entire file

I can't deserialize an entire file because the Deserializer does not implement `into_iter` as other serde libraries do.

How can I get around this?

Code thus far is:

```rust
fn main() -> Result<(), Box> {
let file_path = "./src/foo.msgpack";
let reader = BufReader::new(File::open(file_path).unwrap());
let writer = BufWriter::new(File::create("./src/results.json").unwrap());

let mut deserializer = rmp_serde::Deserializer::from_read(reader);

// let mut serializer = serde_json::Serializer::new(io::stdout());
let mut serializer = serde_json::Serializer::pretty(writer);

serde_transcode::transcode(&mut deserializer, &mut serializer).unwrap();
serializer.into_inner().flush().unwrap();

Ok(())
}
```