A vehicle comprising a rotatable wheel, a forward drive mechanism including a forward drive motor, and a reverse drive mechanism. A software transactional memory system interacts with andor includes a compiler. Once it is determined that the collection threshold is reached, the material forming a first group of material may be transported from the location to the processing area or a subsequent processing area. The scene graph has a notation of the traversing order, which together with the types of nodes, the nodes position, node functionality and node state determine the rendering order.