import time
indent = 0
IndentIncreasing = True

while True :
    print(' ' * indent , end = '')
    print('########')
    time.sleep(0.2)

    if IndentIncreasing :
        indent +=1
        if indent == 10 :
            IndentIncreasing == False

    else :
        indent -=1
        if indent == 0 :
            IndentIncreasing == True