previousCells

Returns this cell and the n-1 previous cells. There should be at least 1 cell returned. The first cell in the returned list is the furthest cell from the current cell. The last cell in the returned list is the current cell. If the conveyor is circular, the returned list may contain cells "before" the starting cell of the first entry cell. If the number of previous cells requested is larger than the number of cells in the conveyor, all cells are returned. If the conveyor is not circular, then the number of cells return may be less than requests because there are no previous cells before the first cell of the conveyor.