code: public static <T extends RemoteRunnable> T runOnH2ONode(T runnable) {
      H2ONode node = H2O.ARGS.client ? H2O.CLOUD.leader() : H2O.SELF;
      return runOnH2ONode(node, runnable);
    }
docs: Executes a runnable on a regular H2O Node (= not on a client).
  If the current H2O Node is a regular node, the runnable will be executed directly (RemoteRunnable#run will be invoked).
  If the current H2O Node is a client node, the runnable will be send to a leader node of the cluster and executed there.
  The caller shouldn't make any assumptions on where the code will be run.
  @param runnable code to be executed
  @param <T> RemoteRunnable
  @return executed runnable (will be a different instance if executed remotely).