This code/sketch drives a bipolar stepper motor. The motor is connected to the Arduino/Genuino board via a A4988 motor driver that is connected to pins 3-5 of the Arduino/Genuino.
The motor will pause a given number of times per one revolution. The number of steps between pauses will be evenly distributed. The motor will then turn the opposite direction and make the same number of pauses per one revolution. You can use this to test that you are capable of making a precise number of steps using your Arduino/Genuino.