String data_in;
String data_out = "I am: MCU ESP32";

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello World!");
}

void loop() {
  // put your main code here, to run repeatedly:
  while( Serial.available())  
  {  
    data_in = Serial.readString();
    Serial.print("Hai: ");
    Serial.println(data_in); 
    Serial.println(data_out);
  }  

  delay(30); // this speeds up the simulation
}