docstr: TODO(qingqing): add comments.
docstr_tok: ["TODO","(","qingqing",")",":","add","comments","."]
code: def __init__(
      self,
      data_shape,
      num_classes=None,
      use_transposed_conv2d=True,
      is_infer=False,
      sub_network=False,
  ):
      """
      TODO(qingqing): add comments.
      """
      self.data_shape = data_shape
      self.min_sizes = [16.0, 32.0, 64.0, 128.0, 256.0, 512.0]
      self.steps = [4.0, 8.0, 16.0, 32.0, 64.0, 128.0]
      self.num_classes = num_classes
      self.use_transposed_conv2d = use_transposed_conv2d
      self.is_infer = is_infer
      self.sub_network = sub_network
  
      # the base network is VGG with atrous layers
      self._input()
      self._vgg()
      if sub_network:
          self._low_level_fpn()
          self._cpm_module()
          self._pyramidbox()
      else:
          self._vgg_ssd()
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import numpy
  import six
  import paddle.fluid
  from paddle.fluid.param_attr import ParamAttr
  from paddle.fluid.initializer import Xavier
  from paddle.fluid.initializer import Constant
  from paddle.fluid.initializer import Bilinear
  from paddle.fluid.regularizer import L2Decay
label_desc: Use image node_id 1 to create a new PyramidBox object from inherited base classes: object with example: obj = PyramidBox(data_shape, num_classes, use_transposed_conv2d, is_infer, sub_network)