Hi there, 

I’m building an app and would like to know how can I fetch klaviyo account id where the user installed my app. 
After we generate the URL and redirect the user in klaviyo, they see the popup in Klaviyo and then confirm/authorize the app to be installed on a specific account they have in Klaviyo. After the confirmation they are redirected in my url, with code and state parameters. 

There is no accountId in this step, and how can I fetch which account id after I generate accessToken and refreshToken. Even if I fetch the list of accounts, how do I know on which account they installed my app? 

Thank you. 
Best regards.