p#define led 3
#define pb 2
#define ditekan  LOW
void setup( )  {
    pinMode(led,  OUTPUT);
    pinMode(pb, INPUT_PULLUP);

}

void loop( )  {
if(digitalRead(pb)==ditekan){
while(digitalRead(pb)==ditekan){}
delay(500);
digitalWrite(led,  !digitalRead(led));
}
}