code: def _refresh_token_flow(self):
          
          url = '%s%s/oauth2/token' % (self.scheme, self.host)
          options = {
              'grant_type': 'refresh_token',
              'client_id': self.options.get('client_id'),
              'client_secret': self.options.get('client_secret'),
              'refresh_token': self.options.get('refresh_token')
          }
          options.update({
              'verify_ssl': self.options.get('verify_ssl', True),
              'proxies': self.options.get('proxies', None)
          })
          self.token = wrapped_resource(
              make_request('post', url, options))
          self.access_token = self.token.access_token
docs: Given a refresh token, obtain a new access token.