```ruby
require "faraday"
require "faraday_middleware"

module Rapa
  class Client
    # @param access_key_id [String]
    # @param associate_tag [String]
    # @param secret_access_key [String]
    def initialize(access_key_id:, associate_tag:, secret_access_key:)
      @access_key_id = access_key_id
      @associate_tag = associate_tag
      @secret_access_key = secret_access_key
    end

    # @return [Faraday::Connection]
    def connection
      @connection ||= ::Faraday::Connection.new do |connection|
        connection.adapter :net_http
        connection.response :xml
      end
    end
  end
end
```

Add private getter as utility
user
```ruby
require "faraday"
require "faraday_middleware"

module Rapa
  class Client
    # @param access_key_id [String]
    # @param associate_tag [String]
    # @param secret_access_key [String]
    def initialize(access_key_id:, associate_tag:, secret_access_key:)
      @access_key_id = access_key_id
      @associate_tag = associate_tag
      @secret_access_key = secret_access_key
    end

    # @return [Faraday::Connection]
    def connection
      @connection ||= ::Faraday::Connection.new do |connection|
        connection.adapter :net_http
        connection.response :xml
      end
    end

    private

    # @private
    # @return [String]
    def access_key_id
      @access_key_id
    end

    # @private
    # @return [String]
    def associate_tag
      @associate_tag
    end

    # @private
    # @return [String]
    def secret_access_key
      @secret_access_key
    end
  end
end
```
assistant