func (s *Server) Ping(node *net.UDPAddr, callback func(krpc.Msg, error)) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.ping(node, callback)
}
func (s *Server) Ping(node *net.UDPAddr, callback func(krpc.Msg, error)) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.ping(node, callback)
}
func ( s * Server ) Ping ( node * net . UDPAddr , callback func ( krpc . Msg , error ) ) error { s . mu . Lock ( ) defer s . mu . Unlock ( ) return s . ping ( node , callback ) }
// Sends a ping query to the address given.
Sends a ping query to the address given .