We're going to build the API for a Mars rover using a test-driven approach. Some things that the rover could do:
* know which compass direction it is facing
* know where it is relative to its landing position
* move forward
* turn left and right
* sense whether there is an obstacle
* refuse to move forward if the path is blocked
* follow a list of single-character commands (f,l,r)
* move backward (b)
* anything else you think would be interesting