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()?