Code 4-1 in black book

const int motor=9 ;
void setup()
{
  pinMode (motor, OUTPUT);
}
void loop()
{
  for (int i=0; i<256; i++)
  {
    analogWrite(motor, i);
    delay(10) ;
  }
  delay (2000) ;
  for (int i=255; i>=0; i--)
  {
    analogWrite(motor, i);
    delay(10) ;
  }
  delay(2000);
}