-------------------------
actual retract: cell(3,2,b)
actual retract: cell(3,3,b)
actual retract: cell(3,3,b)
ff retract: cell(3,2,b)
ff retract: cell(3,3,b)
ff retract: cell(3,3,b)
first([mark(3,2)]).
first([mark(3,3)]).
tt  assert: cell(3,2,o)
tt  assert: cell(3,2,x)
tt  assert: cell(3,3,o)
tt  assert: cell(3,3,x)
