/// <summary>
/// Chooses the next cell that the characters can traverse on, given the previous cell. This function chooses which
/// cells are traversable in the level grid.
/// </summary>
/// <param name="gridNavigator">The navigator which chooses the next traversable cell.</param>
private Cell ChooseNextTraversableCell(Cell cell, GridNavigator gridNavigator)
{
// Stores the directions in which the path may NOT go. That is, if this constant is
// set to 'NavigationDirection.Left', for instance, the next cell CANNOT be to the left
// of the current one. The illegal directions are set to the direction of each of the
// cell's occupied neighbours. That is, if the cell above this one is occupied, the next
// traversable cell cannot be above the current one, since it is already occupied.
NavigationDirection illegalDirections = GetOccupiedNeighbours(cell);
// Choose a direction in which to move to define the next cell in the golden path
NavigationDirection pathDirection = gridNavigator.ChooseDirection(illegalDirections);
// Advance to the next cell in which to continue the current path
cell = GridNavigator.Advance(cell, pathDirection);
// Return the next traversable cell to define in the level grid
return(cell);
}