code: def __init__(
      self,
      octave_base_scale=4,
      scales_per_octave=3,
      aspect_ratios=[0.5, 1.0, 2.0],
      strides=[8.0, 16.0, 32.0, 64.0, 128.0],
      variance=[1.0, 1.0, 1.0, 1.0],
      offset=0.0,
  ):
      anchor_sizes = []
      for s in strides:
          anchor_sizes.append(
              [
                  s * octave_base_scale * 2 ** (i / scales_per_octave)
                  for i in range(scales_per_octave)
              ]
          )
      super(RetinaAnchorGenerator, self).__init__(
          anchor_sizes=anchor_sizes,
          aspect_ratios=aspect_ratios,
          strides=strides,
          variance=variance,
          offset=offset,
      )
  
imports: import math
  import paddle
  import paddle.nn
  import numpy
  from ppdet.core.workspace import register
label_desc: Use image node_id 1 to create a new RetinaAnchorGenerator object from inherited base classes: AnchorGenerator with example: obj = RetinaAnchorGenerator(octave_base_scale, scales_per_octave, aspect_ratios, strides, variance, offset)