```ruby
class APNConnection

  def initialize
    setup
  end

  def setup
    @uri, @certificate = if Rails.env.production? || apn_environment == :production
      [
        Houston::APPLE_PRODUCTION_GATEWAY_URI,
        File.read("#{Rails.root}/config/keys/production_push.pem")
      ]
    else
      [
        Houston::APPLE_DEVELOPMENT_GATEWAY_URI,
        File.read("#{Rails.root}/config/keys/development_push.pem")
      ]
    end

    @connection = Houston::Connection.new(@uri, @certificate, nil)
    @connection.open
  end

  def ssl
    @connection.ssl
  end

  def connection
    @connection
  end

  def write(data)
    raise "Connection is closed" unless @connection.open?
    @connection.write(data)
  end

  private

  def apn_environment
    return nil unless ENV['APN_ENVIRONMENT']

    ENV['APN_ENVIRONMENT'].downcase.to_sym
  end

end```

Put the `APNConnection` class under the `NotifyUser` module.
user
```ruby
module NotifyUser
  class APNConnection

    attr_accessor :connection

    def initialize
      setup
    end

    def setup
      @uri, @certificate = if Rails.env.production? || apn_environment == :production
        [
          ::Houston::APPLE_PRODUCTION_GATEWAY_URI,
          File.read("#{Rails.root}/config/keys/production_push.pem")
        ]
      else
        [
          ::Houston::APPLE_DEVELOPMENT_GATEWAY_URI,
          File.read("#{Rails.root}/config/keys/development_push.pem")
        ]
      end

      @connection = ::Houston::Connection.new(@uri, @certificate, nil)
      @connection.open
    end

    def write(data)
      raise "Connection is closed" unless @connection.open?
      @connection.write(data)
    end

    private

    def apn_environment
      return nil unless ENV['APN_ENVIRONMENT']

      ENV['APN_ENVIRONMENT'].downcase.to_sym
    end

  end
end```
assistant