bool foundSumoBot() {
  // this function returns true if robot near, false if no robot near
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(5);
  digitalWrite(trigPin, LOW);
  long ultrasonicMillis = pulseIn(echoPin, HIGH);
  Serial.println(ultrasonicMillis);
  
  // todo, change number below!
  if (ultrasonicMillis < 5) {
    return true;
  }
  else {
    return false;
  }
}