#define LED 2
#define TASTER 3

//bool flag = LOW;

bool Schalter(bool IN)  {
  static unsigned long millis_alt = millis();
  static bool OUT = LOW;
  static bool flag = LOW;
  if (millis() - millis_alt > 20) {
    millis_alt = millis();
    if (IN == LOW && flag == LOW)  {
      OUT = !OUT;
      flag = HIGH;
    }
    if (IN == HIGH) {
      flag = LOW;
    }
  }
  return OUT;
}


void setup() {
  // put your setup code here, to run once:
  pinMode(LED, OUTPUT);
  pinMode(TASTER, INPUT_PULLUP);
}

void loop() {
  // put your main code here, to run repeatedly:
  bool tstr = Schalter(digitalRead(TASTER));
  digitalWrite(LED, tstr);
}