I feel like we could make this line a little more clear, probably using #inject?

```ruby

rack_env.inject({}) do |hsh, pair| 
  k, v = pair
  hsh[normalize_raygun_header_key(k)] = v
end
```

Where normalize_raygun_header_key is the sub/split/capitalize process you're using there. Let me know if you want me to write that.