code: def access_token(self):
          
          access_token = self.get_auth_bearer()
          if not access_token:
              access_token = self.query_kwargs.get('access_token', '')
              if not access_token:
                  access_token = self.body_kwargs.get('access_token', '')
  
          return access_token
docs: return an Oauth 2.0 Bearer access token if it can be found