Just currently trying to get my head around this API. I have seen the thread recommending to use hard coded data but i also found this in twitch docs so I am going to see what data I can get to play with using my client_id.
Once you create a Developer Application, you are assigned a client id. Some authentication flows also require a client secret. You can generate one on the same page as the client ID. Client IDs are public and can be shared (e.g. embedded in the source of a web page), but client secrets are equivalent to a password for your application and must be kept confidential.