Handle the result of an iteration in _find.

async def _nodes_found(self, responses):
        """
        Handle the result of an iteration in _find.
        """
        toremove = []
        for peerid, response in responses.items():
            response = RPCFindResponse(response)
            if not response.happened():
                toremove.append(peerid)
            else:
                self.nearest.push(response.get_node_list())
        self.nearest.remove(toremove)

        if self.nearest.have_contacted_all():
            return list(self.nearest)
        return await self.find()