World addMorph: (PolygonMorph
shapeFromPen: [:p | p hilbert: 4 side: 5. p go: 5.
p hilbert: 4 side: 5. p go: 5]
color: Color red borderWidth: 1 borderColor: Color black)
Copy the code above to a Workspace and evaluate it.
Found on the class side of PolygonMorph in the method:
shapeFromPen: penBlock color: c borderWidth: bw borderColor: bc
This exemplifies that it's worth to hunt the code for little gems hidden there. Besides that you learn quite a bit by reading the code.