code: def access_token(self):
          
          access = AccessToken()
  
          # Use instantiation time of refresh token as relative timestamp for
          # access token "exp" claim.  This ensures that both a refresh and
          # access token expire relative to the same time if they are created as
          # a pair.
          access.set_exp(from_time=self.current_time)
  
          no_copy = self.no_copy_claims
          for claim, value in self.payload.items():
              if claim in no_copy:
                  continue
              access[claim] = value
  
          return access
docs: Returns an access token created from this refresh token.  Copies all
          claims present in this refresh token to the new access token except
          those claims listed in the `no_copy_claims` attribute.