code: def begin(self, request, data):
          
          request = self.get_request(
                  http_url = self.REQUEST_TOKEN_URL,
                  parameters = dict(oauth_callback = self.get_callback(request)))
          content = self.load_request(request)
          if not content:
              return redirect('netauth-login')
          request = self.get_request(token = Token.from_string(content), http_url=self.AUTHORIZE_URL)
          return redirect(request.to_url())
docs: Try to get Request Token from OAuth Provider and
              redirect user to provider's site for approval.