Function redsyncmodulelib::get_key_fetch_token

pub async fn get_key_fetch_token(usr: String, pw: String) -> String

This function fetches the keyFetchToken from the auth server. It is the first expected to be used in the library. From there, you will have to inform the user about verification, and then you should be able to continue. We only return the bare minimal for the next function. If error, this returns a message with the error instead of the TokenResponse.