@type t() :: %Paypal.Auth.Access{
  access_token: String.t() | nil,
  app_id: String.t() | nil,
  expires_in: integer() | nil,
  nonce: String.t() | nil,
  scope: String.t() | nil,
  token_type: String.t() | nil
}

The information stored inside of the access structure is the following:

• scope is a list of URLs we can access or use with the access token.
• access_token is the hash we need for the other requests.
• token_type is the type of the token generated. Usually it's Bearer.
• app_id is the ID of the application.
• expires_in is the number of seconds for expiring the token.
• nonce is the nonce used.