code: func (a *AddrManager) Connected(addr *wire.NetAddress) {
  	a.mtx.Lock()
  	defer a.mtx.Unlock()
  
  	ka := a.find(addr)
  	if ka == nil {
  		return
  	}
  
  	// Update the time as long as it has been 20 minutes since last we did
  	// so.
  	now := time.Now()
  	if now.After(ka.na.Timestamp.Add(time.Minute * 20)) {
  		// ka.na is immutable, so replace it.
  		naCopy := *ka.na
  		naCopy.Timestamp = time.Now()
  		ka.na = &naCopy
  	}
  }
docs: // Connected Marks the given address as currently connected and working at the
  // current time.  The address must already be known to AddrManager else it will
  // be ignored.