code: func (t *UDPv4) LookupRandom() []*enode.Node {
  	if t.tab.len() == 0 {
  		// All nodes were dropped, refresh. The very first query will hit this
  		// case and run the bootstrapping logic.
  		<-t.tab.refresh()
  	}
  	return t.lookupRandom()
  }
docs: // LookupRandom finds random nodes in the network.