code: def access(self, client_id, client_secret, code, **kwargs):
          
          self.params.update({
              'client_id':     client_id,
              'client_secret': client_secret,
              'code':          code,
              })
          if kwargs:
              self.params.update(kwargs)
          return FromUrl('https://slack.com/api/oauth.access', self._requests)(data=self.params).post()
docs: https://api.slack.com/methods/oauth.access