Write a program that causes the built-in LED connected to pin 13 on the Arduino to blink, alternating between fast blinks and slow blinks. The LED should blink 5 times quickly and then it should blink 5 more times slowly. When blinking quickly, the LED should have a 1 second period, so it should be high for 0.5 seconds and low for 0.5 seconds. When blinking slowly, the LED should have a 4 second period, so it should be high for 2 seconds and low for 2 seconds. The LED should continue to blink in this alternating fashion for as long as the Arduino receives power.