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: PaddleDetection/ppdet/modeling/architectures/keypoint_petr.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import paddle
  from ppdet.core.workspace import register
  from .meta_arch import BaseArch
  from ..None import layers
label_desc: Use image node_id 2 for calling the PETR obj's underlying member method code with example usage: obj.extract_feat(img) and returns: x