Modify a trusted peer device by deploying an iapp.


        :param truster: ManagementRoot object -- device on which to perform
                        commands
        :param mod_peer_func: function -- function to call to modify peer
        :param trustee: ManagementRoot object or str -- device to modify

def _modify_trust(self, truster, mod_peer_func, trustee):
        '''Modify a trusted peer device by deploying an iapp.


        :param truster: ManagementRoot object -- device on which to perform
                        commands
        :param mod_peer_func: function -- function to call to modify peer
        :param trustee: ManagementRoot object or str -- device to modify
        '''

        iapp_name = 'trusted_device'
        mod_peer_cmd = mod_peer_func(trustee)
        iapp_actions = self.iapp_actions.copy()
        iapp_actions['definition']['implementation'] = mod_peer_cmd
        self._deploy_iapp(iapp_name, iapp_actions, truster)
        self._delete_iapp(iapp_name, truster)