class_docstr: Describes backbone information and provides utility functions.
      
class_docstr_tok: ["Describes","backbone","information","and","provides","utility","functions","."]
docstr: Checks whether the backbone string is correct.
          
docstr_tok: ["Checks","whether","the","backbone","string","is","correct","."]
code: def validate(self):
      """Checks whether the backbone string is correct."""
      allowed_backbones = ["vgg16", "vgg19"]
  
      if self.backbone not in allowed_backbones:
          raise ValueError(
              "Backbone ('{}') not in allowed backbones ({}).".format(
                  self.backbone, allowed_backbones
              )
          )
  
file_path: ImageAI/imageai_tf_deprecated/Detection/keras_retinanet/models/vgg.py
imports: from tensorflow import keras
  from .None import retinanet
  from .None import Backbone
  from ..utils.image import preprocess_image
label_desc: Use image node_id 3 for calling the VGGBackbone obj's underlying member method code with example usage: obj.validate() without return types