code: public int invokeOnNodes (Function<Tuple<Client,NodeObject>,Boolean> func)
      {
          int invoked = 0;
          for (PeerNode peer : _peers.values()) {
              if (peer.nodeobj != null) {
                  if (func.apply(Tuple.newTuple(peer.getClient(), peer.nodeobj))) {
                      invoked++;
                  }
              }
          }
          return invoked;
      }
docs: Invokes the supplied function on <em>all</em> node objects (except the local node). A caller
  that needs to call an invocation service method on a remote node should use this mechanism
  to locate the appropriate node (or nodes) and call the desired method.
  
  @return the number of times the invoked function returned true.