const int pinone = 13; 

int ledState = LOW; // the switch which sould vary with the program later

int previousMillis = 0;

int interval = 1000; // the two variables are used for algoritm later?

void setup() {// the setup part runs one
  
  pinMode(pinone, OUTPUT); /*set the variable pineone as an output. 
  pinone has an integer constant value of 13 which is what 
  the arduion takes as the hardware pin number */

}

void loop() {
  
  //algorithm:
// check to see if it's time to blink the LED; that is, if the
// difference between the current time and last time you blinked
// the LED is bigger than the interval at which you want to
// blink the LED.
unsigned long currentMillis = millis();
if(currentMillis - previousMillis > 800) {
// save the last time you blinked the LED
previousMillis = millis();
// if the LED is off turn it on and vice-versa:
if (ledState == LOW)
ledState = HIGH;
else
ledState = LOW;
// set the LED with the ledState of the variable:
digitalWrite(pinone, ledState);

}
}