code: def new_signing_keys(self):
          
          if self._new_signing_keys is None:
              self._new_signing_keys = NewSigningKeyList(self._version, account_sid=self._solution['sid'], )
          return self._new_signing_keys
docs: Access the new_signing_keys
  
          :returns: twilio.rest.api.v2010.account.new_signing_key.NewSigningKeyList
          :rtype: twilio.rest.api.v2010.account.new_signing_key.NewSigningKeyList