Trying to read different gas levels with MQ2 Gas Sensor
First this should be like this:

float* values= mq2.read(false); //false


and then write this to be printed in the serial monitor

Serial.print('\n');
  Serial.print("LPG:");
  Serial.print(lpg);
  Serial.print(" CO:");
  Serial.print(co);

  Serial.print('\n');
  Serial.print("SMOKE:");
  Serial.print(smoke);
  Serial.print(" PPM");
  Serial.print('\n');