```ruby
require 'spree_core'
require 'spree_amazon_fps/engine'
require 'amazon/fps/signature_utils'
```

Add new api system to library
user
```ruby
require 'spree_core'
require 'spree_amazon_fps/engine'
require 'amazon/fps/signature_utils'
require 'amazon/fps/api_call'
```
assistant