code: def welcome_if_new(self, node):
          
          if not self.router.is_new_node(node):
              return
  
          log.info("never seen %s before, adding to router", node)
          for key, value in self.storage:
              keynode = Node(digest(key))
              neighbors = self.router.find_neighbors(keynode)
              if neighbors:
                  last = neighbors[-1].distance_to(keynode)
                  new_node_close = node.distance_to(keynode) < last
                  first = neighbors[0].distance_to(keynode)
                  this_closest = self.source_node.distance_to(keynode) < first
              if not neighbors or (new_node_close and this_closest):
                  asyncio.ensure_future(self.call_store(node, key, value))
          self.router.add_contact(node)
docs: Given a new node, send it all the keys/values it should be storing,
          then add it to the routing table.
  
          @param node: A new node that just joined (or that we just found out
          about).
  
          Process:
          For each key in storage, get k closest nodes.  If newnode is closer
          than the furtherst in that list, and the node for this server
          is closer than the closest in that list, then store the key/value
          on the new node (per section 2.5 of the paper)