class_docstr: Simple stem for ImageNet: 3x3, BN, AF.
class_docstr_tok: ["Simple","stem","for","ImageNet",":","3x3",",","BN",",","AF","."]
code: def forward(self, x):
      for layer in self.children():
          x = layer(x)
      return x
  
imports: import numpy
  from torch import nn
  from detectron2.layers import CNNBlockBase, ShapeSpec, get_norm
  from .backbone import Backbone
label_desc: Use image node_id 2 for calling the SimpleStem obj's underlying member method code with example usage: obj.forward(x) and returns: x