/// <summary>
/// change the node and position of a nodeDisplay to a node at the given index
/// </summary>
/// <param name="display"></param> NodeDisplay to modify
/// <param name="index"></param> index of node to change display to
public void setUpNodeDisplay(NodeDisplay display, int index)
{
display.changeNode(get_ith_node(index));
display.setPosition(get_ith_position(index));
}
