+# Plot a Menger sponge.
+#
+# The construction of a Menger sponge can be described as follows:
+#
+# 1. Begin with a cube.
+# 2. Divide every face of the cube into 9 squares, like a Rubik's Cube. This
+# will sub-divide the cube into 27 smaller cubes.
+# 3. Remove the smaller cube in the middle of each face, and remove the smaller
+# cube in the very center of the larger cube, leaving 20 smaller cubes. This
+# is a level-1 Menger sponge (resembling a Void Cube).
+# 4. Repeat steps 2 and 3 for each of the remaining smaller cubes, and continue
+# to iterate.
+