我用了官方的mnist的例子，然后现在我想输入一个图片，然后写一个预测程序，显示出来每个数字的概率，代码如下，请大神帮看看问题在哪？

import paddle.fluid as fluid
import numpy
import paddle # 导入paddle模块
from PIL import Image

train_pic = paddle.dataset.mnist.train()
pic_data = []
count = 0
for id,data in enumerate(train_pic()):
if count == 1:
break
pic_data = data
count = count+1

print(pic_data[0])

img = fluid.layers.data(name='img', shape=[1,28,28], dtype='float32')

predict = fluid.layers.fc(input=img, size=10, act='softmax')

cpu = fluid.core.CPUPlace()
exe = fluid.Executor(cpu)

fluid.io.load_inference_model("recognize_digits.inference.model",
exe,
model_filename=None,
params_filename=None)

prog = fluid.default_main_program()

exe.run(prog)
res=[]
outs = exe.run(
feed={'img': pic_data[0]},
fetch_list=res)

print("----------------------------")
print(res)