MagicGenerator

def give_next(prev_row, prev_blocks_list, prob=0.3):
    row = ''
    for _ in prev_row:
        row += '█' if random.random() <= prob else '░'
    for block in prev_blocks_list:
        i = random.choice(block)
        row = row[:i] + '█' + row[i+1:]
    blocks_list = []
    block = []
    for i, ch in enumerate(row):
        if ch == '█':
            block.append(i)
        elif block:
            blocks_list.append(block)
            block = []
    if block:
        blocks_list.append(block)
    return row, blocks_list
block = ' '*20
blocks_list = []
for i in range(100):
    block, blocks_list = give_next(block, blocks_list)
    print(block)