def vertical_random_walk(size):
    """
    Generates random walks that start at the left side of the image and move towards the right
    :param size: The size of the image
    :return: An iterator of paths, each an iterator of (x,y) coordinates
    """
    width, _ = size
    distribution = {(dx, 1): 1 / 3.0 for dx in [-1, 0, 1]}
    start_points = [(x, 0) for x in range(width)]
    return random_walk_path(size, distribution, start_points)
def vertical_random_walk ( size ) : width , _ = size distribution = { ( dx , 1 ) : 1 / 3.0 for dx in [ - 1 , 0 , 1 ] } start_points = [ ( x , 0 ) for x in range ( width ) ] return random_walk_path ( size , distribution , start_points )
Generates random walks that start at the left side of the image and move towards the right
    :param size: The size of the image
    :return: An iterator of paths, each an iterator of (x,y) coordinates