code: async def bootstrap(self, addrs):
          
          log.debug("Attempting to bootstrap node with %i initial contacts",
                    len(addrs))
          cos = list(map(self.bootstrap_node, addrs))
          gathered = await asyncio.gather(*cos)
          nodes = [node for node in gathered if node is not None]
          spider = NodeSpiderCrawl(self.protocol, self.node, nodes,
                                   self.ksize, self.alpha)
          return await spider.find()
docs: Bootstrap the server by connecting to other known nodes in the network.
  
          Args:
              addrs: A `list` of (ip, port) `tuple` pairs.  Note that only IP
                     addresses are acceptable - hostnames will cause an error.