I was trying to solve a problem called How Big Are the Pockets? from Codejam.
Basically they want you to count the number of shaded squares in a figure like follows.
They give you as input a sequence of movements (right, left, or forward):
9
F 6 R 1 F 4 RFF 2 LFF 1
LFFFR 1 F 2 R 1 F 5
In order to debug my solution I made a program that draws the line path and a trace of my solution.
I found some cool figures in the input test cases.
This one looks like a face:
