class_docstr: Base class for single-stage detectors.
  
  Single-stage detectors directly and densely predict bounding boxes on the
  output features of the backbone+neck.
docstr: Directly extract features from the backbone+neck.
docstr_tok: ["Directly","extract","features","from","the","backbone+neck","."]
code: def extract_feat(self, img):
      """Directly extract features from the backbone+neck."""
      x = self.backbone(img)
      if self.with_neck:
          x = self.neck(x)
      return x
  
file_path: insightface/detection/scrfd/mmdet/models/detectors/single_stage.py
imports: import torch
  import torch.nn
  from mmdet.core import bbox2result
  from ..builder import DETECTORS, build_backbone, build_head, build_neck
  from .base import BaseDetector
label_desc: Use image node_id 3 for calling the SingleStageDetector obj's underlying member method code with example usage: obj.extract_feat(img) and returns: x