code: def refresh(self):
          "Refresh an expired token"
  
          # Construct the credentials for the verification request
          oauth = OAuth1(
              self.consumer_key,
              client_secret=self.consumer_secret,
              resource_owner_key=self.oauth_token,
              resource_owner_secret=self.oauth_token_secret,
              rsa_key=self.rsa_key,
              signature_method=self._signature_method
          )
  
          # Make the verification request, getting back an access token
          headers = {'User-Agent': self.user_agent}
          params = {'oauth_session_handle': self.oauth_session_handle}
          response = requests.post(url=self.base_url + ACCESS_TOKEN_URL,
                  params=params, headers=headers, auth=oauth)
          self._process_oauth_response(responsef refresh(self):
          "Refresh an expired token"
  
          # Construct the credentials for the verification request
          oauth = OAuth1(
              self.consumer_key,
              client_secret=self.consumer_secret,
              resource_owner_key=self.oauth_token,
              resource_owner_secret=self.oauth_token_secret,
              rsa_key=self.rsa_key,
              signature_method=self._signature_method
          )
  
          # Make the verification request, getting back an access token
          headers = {'User-Agent': self.user_agent}
          params = {'oauth_session_handle': self.oauth_session_handle}
          response = requests.post(url=self.base_url + ACCESS_TOKEN_URL,
                  params=params, headers=headers, auth=oauth)
          self._process_oauth_response(response)
docs: Refresh an expired token