docs: def authorize_url(self, client_id, redirect_uri, scope, state=None):
          """Get the authorization URL for your application, given the application's
          client_id, redirect_uri, scope, and optional state data."""
          params = [
              ('client_id', client_id),
              ('redirect_uri', redirect_uri),
              ('scope', scope)
          ]
          if state:
              params.append(('state', state))
          return "%s?%s" % (CreateSend.oauth_uri, urlencode(params))