model.summary()以以下格式提供模型信息：
Layer (type) Output Shape Param # Connected to
==============================================================================
input_1 (InputLayer) (None, 50, 50, 1) 0
______________________________________________________________________________
conv2d_1 (Conv2D) (None, 48, 48, 4) 40 input_1[0][0]
______________________________________________________________________________
conv2d_2 (Conv2D) (None, 46, 46, 4) 148 conv2d_1[0][0]
______________________________________________________________________________
我想知道层的序列号，如下所示：
S. No. Layer (type) Output Shape Param # Connected to
==============================================================================
0 input_1 (InputLayer) (None, 50, 50, 1) 0
______________________________________________________________________________
1 conv2d_1 (Conv2D) (None, 48, 48, 4) 40 input_1[0][0]
______________________________________________________________________________
2 conv2d_2 (Conv2D) (None, 46, 46, 4) 148 conv2d_1[0][0]
______________________________________________________________________________
如何为此编写keras代码？