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void setup() {
  // put your setup code here, to run once:
  pinMode(12, OUTPUT);
  Serial.begin(115200);
}

void loop() {
  // put your main code here, to run repeatedly:

  if(Serial.available() > 0){//Read from serial monitor and send over HC-12
    String input = Serial.readString();
    Serial.println(input);

    //Now test string for appropriate action
    if (input == "hi") {
      Serial.println("bye");
      digitalWrite(12, HIGH);  // We have an active-low LED attached
    } else {
      digitalWrite(12, LOW);  // We have an active-low LED attached
    }
  }

  delay(20);
}