code: def from_config(cls, cfg, input_shape):
      return {
          "in_channels": [i.channels for i in input_shape],
      }
  
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddle import ParamAttr
  from paddle.regularizer import L2Decay
  from ppdet.core.workspace import register
  import math
  import numpy
  from ..initializer import bias_init_with_prob, constant_
  from ..backbones.csp_darknet import BaseConv, DWConv
  from ..losses import IouLoss
  from ppdet.modeling.assigners.simota_assigner import SimOTAAssigner
  from ppdet.modeling.bbox_utils import bbox_overlaps
  from ppdet.modeling.layers import MultiClassNMS
label_desc: Use image node_id 4 for calling the YOLOv3Head obj's underlying member method code with example usage: obj.from_config(cls, cfg, input_shape) and returns: dict