Used to add a new node on Sovrin
        :param node: Node
        :return: number of pending txns

def addNode(self, node: Node):
        """
        Used to add a new node on Sovrin
        :param node: Node
        :return: number of pending txns
        """
        self._nodes[node.id] = node
        req = node.ledgerRequest()
        if req:
            self.pendRequest(req, node.id)
        return len(self._pending)