class_docstr: Stem Layer as defined in https://arxiv.org/abs/1710.02238. The structure is
  significantly altered from the original Inception-ResNet architecture,
  (https://arxiv.org/abs/1602.07261) but the idea behind this layer is to
  downsample the image as a preprocessing step for the Inception-ResNet layers,
  and reduce computational complexity.
docstr: Invoked when __call__ method of the layer is used.
docstr_tok: ["Invoked","when","__call__","method","of","the","layer","is","used","."]
code: def call(self, inputs):
      """Invoked when __call__ method of the layer is used."""
      conv1 = self.conv_layer(inputs)
      return self.activation_layer(conv1)
  
imports: import tensorflow
  from tensorflow.keras.layers import Conv2D, Concatenate, ReLU, Add, MaxPool2D
label_desc: Use image node_id 3 for calling the Stem obj's underlying member method code with example usage: obj.call(inputs) and returns: self