Working through this constrained vtkDelaunay2D example: One line confuses me

This example script linked below generates a surface with a vtk-shaped hole using vtkDelaunay2D. I think I understand the all of the script except for line 94: polys.InsertNextCell(28)

The script generates outer points and inner points, and a vtkCellArray. The cell array adds the first inner point (line 81) and then all outer points counter-clockwise (lines 92-93). Then the array adds point 28 (line 94), then all inner points clockwise (line 95-122)

If I comment out line 94, the hole collapses.

My question: Why is line 94 necessary?

[edit] - It was a misreading on my part. It is not inserting cell point 28, it is inserting the next cell which will contain 28 points