Rust function returned string lifetimes
I have a function which does a lookup on a mapping of a global int -> str, returning the string.
https://github.com/swift-nav/piksi_tools/blob/55d5d4e/piksi_tools/console/utils.py#L510-L513

With https://github.com/adsharma/py2many/pull/249, the dict aspect is working (almost: `rustup run nightly cargo clippy --fix -Z unstable-options` fixes one problem), however one problem remains:

```rust
416 | pub fn code_to_str(code: i32) -> &str {
    |                                  ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value with an elided lifetime, but the lifetime cannot be derived from the arguments
help: consider using the `'static` lifetime

416 | pub fn code_to_str(code: i32) -> &'static str {
```

(note I have a tiny script which preprocesses ^ that `utils.py` to remove the imports, excludes `color_dict` (multi type mapping values) and stops at `get_mode` (which depends on imports, and stuff afterwards depends on Python stdlib or runtime).)