 data, reading headers and cookies. By default this is a function that returns <code>options.deserialize(parsedResponse)</code>, throwing an exception when the server response status code indicates an error or when the response is syntactically invalid. If a custom <code>extract</code> callback is provided, the <code>xhr</code> parameter is the XMLHttpRequest instance used for the request, and <code>options</code> is the object that was passed to the <code>m.request</code> call. Additionally, <code>deserial