    def __init__(self,
                 ch_in,
                 ch_out,
                 norm_type='bn',
                 norm_decay=0.,
                 freeze_norm=False,
                 data_format='NCHW'):
        """
        BasicBlock layer of DarkNet
        Args:
            ch_in (int): input channel
            ch_out (int): output channel
            norm_type (str): batch norm type, default bn
            norm_decay (str): decay for weight and bias of batch norm layer, default 0.
            freeze_norm (bool): whether to freeze norm, default False
            data_format (str): data format, NCHW or NHWC
        """

        super(BasicBlock, self).__init__()

        self.conv1 = ConvBNLayer(
            ch_in=ch_in,
            ch_out=ch_out,
            filter_size=1,
            stride=1,
            padding=0,
            norm_type=norm_type,
            norm_decay=norm_decay,
            freeze_norm=freeze_norm,
            data_format=data_format)
        self.conv2 = ConvBNLayer(
            ch_in=ch_out,
            ch_out=ch_out * 2,
            filter_size=3,
            stride=1,
            padding=1,
            norm_type=norm_type,
            norm_decay=norm_decay,
            freeze_norm=freeze_norm,
            data_format=data_format)
BasicBlock layer of DarkNet
Args:
ch_in (int): input channel
ch_out (int): output channel
norm_type (str): batch norm type, default bn
norm_decay (str): decay for weight and bias of batch norm layer, default 0.
freeze_norm (bool): whether to freeze norm, default False
data_format (str): data format, NCHW or NHWC
ptstructure/layout/ptppyolov2/ppyolov2_darknet.py