class_docstr: AnchorGenerator by paddle
class_docstr_tok: ["AnchorGenerator","by","paddle"]
code: def num_base_anchors(self):
      return self.base_anchors.shape[0]
  
imports: import math
  import paddle
  import paddle.nn
  import numpy
  from ppdet.core.workspace import register
label_desc: Use image node_id 2 for calling the S2ANetAnchorGenerator obj's underlying member method code with example usage: obj.num_base_anchors() and returns: self