code: def _check_jwt_claims(jwt_claims):
      
      current_time = time.time()
  
      expiration = jwt_claims[u"exp"]
      if not isinstance(expiration, INT_TYPES):
          raise suppliers.UnauthenticatedException(u'Malformed claim: "exp" must be an integer')
      if current_time >= expiration:
          raise suppliers.UnauthenticatedException(u"The auth token has already expired")
  
      if u"nbf" not in jwt_claims:
          return
  
      not_before_time = jwt_claims[u"nbf"]
      if not isinstance(not_before_time, INT_TYPES):
          raise suppliers.UnauthenticatedException(u'Malformed claim: "nbf" must be an integer')
      if current_time < not_before_time:
          raise suppliers.UnauthenticatedException(u'Current time is less than the "nbf" time')
docs: Checks whether the JWT claims should be accepted.
  
      Specifically, this method checks the "exp" claim and the "nbf" claim (if
      present), and raises UnauthenticatedException if 1) the current time is
      before the time identified by the "nbf" claim, or 2) the current time is
      equal to or after the time identified by the "exp" claim.
  
      Args:
        jwt_claims: the JWT claims whose expiratio to be checked.
  
      Raises:
        UnauthenticatedException: When the "exp" claim is malformed or the JWT has
          already expired.