def __init__()

in segmentation/model/cnsn_resnet.py [0:0]


    def __init__(self, block, layers, num_classes=1000, zero_init_residual=False,
                 groups=1, width_per_group=64, replace_stride_with_dilation=None,
                 norm_layer=None, block_idxs=None, active_num=None, pos=None, beta=None, crop=None, cnsn_type=None, cn_pos=None):
        super(ResNet, self).__init__()
        if norm_layer is None:
            norm_layer = nn.BatchNorm2d
        self._norm_layer = norm_layer

        self.inplanes = 64
        self.dilation = 1
        if replace_stride_with_dilation is None:
            # each element in the tuple indicates if we should replace
            # the 2x2 stride with a dilated convolution instead
            replace_stride_with_dilation = [False, False, False]
        if len(replace_stride_with_dilation) != 3:
            raise ValueError("replace_stride_with_dilation should be None "
                             "or a 3-element tuple, got {}".format(replace_stride_with_dilation))
        self.groups = groups
        self.base_width = width_per_group
        
        if block_idxs:
            block_idxs = block_idxs.split('_')
            block_idxs = list(map(int, block_idxs))
        print('block_idxs: {}'.format(block_idxs))
        if beta is not None:
            print('beta: {}'.format(beta))

        if crop is not None:
            print('crop in 2 instance mode: {}'.format(crop))


        self.block_idxs = block_idxs
        if block_idxs and 0 in block_idxs:
            self.img_cn = CrossNorm(crop=crop, beta=beta)
        self.conv1 = nn.Conv2d(3, self.inplanes, kernel_size=7, stride=2, padding=3,
                               bias=False)
        self.bn1 = norm_layer(self.inplanes)
        self.relu = nn.ReLU(inplace=True)
        self.maxpool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1)

        if block_idxs and 1 in block_idxs:
            self.layer1 = self._make_layer(block, 64, layers[0], pos=pos, beta=beta, crop=crop, cnsn_type=cnsn_type, cn_pos=cn_pos, custom=True)
        else:
            self.layer1 = self._make_layer(block, 64, layers[0], custom=False)

        if block_idxs and 2 in block_idxs:
            self.layer2 = self._make_layer(block, 128, layers[1], stride=2, dilate=replace_stride_with_dilation[0], pos=pos, beta=beta, crop=crop, cnsn_type=cnsn_type, cn_pos=cn_pos, custom=True)
        else:
            self.layer2 = self._make_layer(block, 128, layers[1], stride=2,
                                       dilate=replace_stride_with_dilation[0], custom=False)
        
        if block_idxs and 3 in block_idxs:
            self.layer3 = self._make_layer(block, 256, layers[2], stride=2, dilate=replace_stride_with_dilation[1], pos=pos, beta=beta, crop=crop, cnsn_type=cnsn_type, cn_pos=cn_pos, custom=True)    
        else:
            self.layer3 = self._make_layer(block, 256, layers[2], stride=2,
                                       dilate=replace_stride_with_dilation[1], custom=False)

        if block_idxs and 4 in block_idxs:
            self.layer4 = self._make_layer(block, 512, layers[3], stride=2, dilate=replace_stride_with_dilation[2], pos=pos, beta=beta, crop=crop, cnsn_type=cnsn_type, cn_pos=cn_pos, custom=True)
        else:
            self.layer4 = self._make_layer(block, 512, layers[3], stride=2,
                                       dilate=replace_stride_with_dilation[2], custom=False)
        self.fc = nn.Linear(512 * block.expansion, num_classes)
        

        self.cn_modules = []

        for m in self.modules():
            if isinstance(m, nn.Conv2d):
                nn.init.kaiming_normal_(m.weight, mode='fan_out', nonlinearity='relu')
            elif isinstance(m, (nn.BatchNorm2d, nn.GroupNorm)):
                nn.init.constant_(m.weight, 1)
                nn.init.constant_(m.bias, 0)
            elif isinstance(m, nn.Linear) and m.bias is not None:
                m.bias.data.zero_()
            elif isinstance(m, CrossNorm):
                self.cn_modules.append(m)

        if 'cn' in cnsn_type or cn_pos is not None:
            self.cn_num = len(self.cn_modules)
            assert self.cn_num > 0
            print('cn_num: {}'.format(self.cn_num))
            self.active_num = active_num
            assert self.active_num > 0
            print('active_num: {}'.format(self.active_num))


        # Zero-initialize the last BN in each residual branch,
        # so that the residual branch starts with zeros, and each residual block behaves like an identity.
        # This improves the model by 0.2~0.3% according to https://arxiv.org/abs/1706.02677
        if zero_init_residual:
            for m in self.modules():
                if isinstance(m, Bottleneck):
                    nn.init.constant_(m.bn3.weight, 0)
                elif isinstance(m, BasicBlock):
                    nn.init.constant_(m.bn2.weight, 0)