Let's put this file right in your home directory for simplicity. The wget command makes things easy as this can be run from an internet connected Raspberry Pi.
$ wget https://raw.githubusercontent.com/adafruit/Adafruit_Learning_System_Guides/master/Raspberry_Pi_Stepper_Motors/Raspberry_Pi_Stepper_Motors.py
Confirm that the Pi connected to the Cobbler (or Cobbler Plus) and run the script.
The following command will start the program:
$ sudo python3 ./Raspberry_Pi_Stepper_Motors.py
Enter a delay (5 is a good value) and then a number of steps (512 is a full rotation).
Experiment reducing the delay to find the maximum speed of the motor.
