src/transformers/models/efficientformer/modeling_efficientformer.py/EfficientFormerConvStem/__init__
class EfficientFormerConvStem:    def __init__(self, config: EfficientFormerConfig, out_channels: int):
        super().__init__()

        self.convolution1 = nn.Conv2d(config.num_channels, out_channels // 2, kernel_size=3, stride=2, padding=1)
        self.batchnorm_before = nn.BatchNorm2d(out_channels // 2)

        self.convolution2 = nn.Conv2d(out_channels // 2, out_channels, kernel_size=3, stride=2, padding=1)
        self.batchnorm_after = nn.BatchNorm2d(out_channels)

        self.activation = nn.ReLU()