code: def update_features(self, feat):
      feat /= np.linalg.norm(feat)
      self.curr_feat = feat
      if self.smooth_feat is None:
          self.smooth_feat = feat
      else:
          self.smooth_feat = (
              self.alpha * self.smooth_feat + (1 - self.alpha) * feat
          )
      self.features.append(feat)
      self.smooth_feat /= np.linalg.norm(self.smooth_feat)
  
imports: import numpy
  from collections import deque, OrderedDict
  from ..matching import jde_matching
  from ppdet.core.workspace import register, serializable
label_desc: Use image node_id 2 for calling the STrack obj's underlying member method code with example usage: obj.update_features(feat) without return types