I figured a different way by adding a field in the current agent to save
the last state then hide it by giving it a new state of EMPTY -- and then
storing that new state (EMPTY) on the (schelling)state location of the
agent. It also allows me to simulate death of that agent if another agent
moved into that cell.
New question: I've got to access the grid created in Schelling after
createGrids(). I tried to access it through neighbors but got an empty
grid in the new function I created to access the grid. How would I access
the grid created by createGrids()?