code: def valid_service_context(service_context, when=0):
      
      eta = getattr(service_context, 'client_secret_expires_at', 0)
      now = when or utc_time_sans_frac()
      if eta != 0 and eta < now:
          return False
      return True
docs: Check if the client_secret has expired
  
      :param service_context: A
          :py:class:`oidcservice.service_context.ServiceContext` instance
      :param when: A time stamp against which the expiration time is to be checked
      :return: True if the client_secret is still valid