code: def complete(self, GET):
          
          token = self.get_access_token(verifier=GET.get('oauth_verifier', None))
          return token
docs: When redirect back to our application, try to complete the flow by
          requesting an access token. If the access token request fails, it'll
          throw an `OAuthError`.
          
          Tries to complete the flow by validating against the `GET` paramters 
          received.