def tile_walk(start_cell, direction, num_steps):
    """
    Helper function that returns a list of points based on a
    starting point and a direction.
    """
    
    templst = []
    for step in range(num_steps):
        row = start_cell[0] + step * direction[0]
        col = start_cell[1] + step * direction[1]
        templst.append((row, col))
        
    return templst