Core 1

int sendLedPin = D7;
int inputPin = D4;
int receiveLedPin = D0;
int receiveLedPin2 = D6;
int lastVal = 0;
int sendLedVal = 0;
void ledTwoToggle(const char *toggle, const char *onOff); //handler function for Spark.subscribe()


void setup()
{
  pinMode(receiveLedPin, OUTPUT);
  pinMode(receiveLedPin2, OUTPUT);
  pinMode(sendLedPin, OUTPUT);
  pinMode(inputPin, INPUT_PULLUP);
  digitalWrite(sendLedPin, LOW);
  digitalWrite(receiveLedPin, LOW);
  digitalWrite(receiveLedPin2, LOW);
  Spark.publish("Core1Toggle", "State", 0);
  Spark.subscribe("Core2Toggle", ledTwoToggle);
  Spark.subscribe("Core3Toggle", ledTwoToggle2);
}


void loop()
{
  static unsigned long lastPressTime =0;
  int val = digitalRead(inputPin);
  if (val == LOW && lastVal == HIGH)
  {
    if (millis() - lastPressTime > 25UL) //less primitive (non-blocking) debounce time
    {
      sendLedVal = !sendLedVal;
      digitalWrite(sendLedPin, sendLedVal ? HIGH : LOW);
      Spark.publish("Core1Toggle", sendLedVal ? "ON" : "OFF");
    }
    lastPressTime = millis();
  }
  lastVal = val;
}

void ledTwoToggle(const char *toggle, const char *onOff)
{
  if (strcmp(onOff, "OFF") == 0)
  {
    digitalWrite(receiveLedPin, LOW);
  }
  else if (strcmp(onOff, "ON") == 0)
  {
    digitalWrite(receiveLedPin, HIGH);
  }
}

void ledTwoToggle2(const char *toggle, const char *onOff)
{
  if (strcmp(onOff, "OFF") == 0)
  {
    digitalWrite(receiveLedPin2, LOW);
  }
  else if (strcmp(onOff, "ON") == 0)
  {
    digitalWrite(receiveLedPin2, HIGH);
  }
}