statement seems to have no effect怎么解决

def Petal(m,t):
for i in range(m):
a = 200 -400 * random()
......

def Petal(m,t):
for i in range(m):
a = 200 -400 * random()//这句是否忘记缩进了？要不循环好像在空驶。有帮助请采纳，谢谢！