code: def get_extra_claims(self, claims_set):
          
          reserved_claims = (
              self.userid_claim, "iss", "aud", "exp", "nbf", "iat", "jti",
              "refresh_until", "nonce"
          )
          extra_claims = {}
          for claim in claims_set:
              if claim not in reserved_claims:
                  extra_claims[claim] = claims_set[claim]
          if not extra_claims:
              return None
  
          return extra_claims
docs: Get claims holding extra identity info from the claims set.
  
          Returns a dictionary of extra claims or None if there are none.
  
          :param claims_set: set of claims, which was included in the received
          token.