example.ino

void setup () {
  // do what ever to get it all set up
  // only ran once at poweron
}

void main () {
  if (sensorpin is low && analogread value less than x) {
    set pin high
  }
  
  if (sensorpin high && analogread value above y) {
    set pin back down to low
  }
  
  //when it gets to here it goes back to the start of the main loop. 
  // so it might try those statements 1000 times before the sensorvalue 
  // gets high enough for the second if statement to switch the pin back down 
}