class_docstr: EfficientDet keras network with train and test step.
code: def _freeze_vars(self):
      if self.config.var_freeze_expr:
          return [
              v
              for v in self.trainable_variables
              if not re.match(self.config.var_freeze_expr, v.name)
          ]
      return self.trainable_variables
  
imports: import functools
  from absl import logging
  import tensorflow
  import hparams_config
  import utils
  from .backbone import efficientnet_builder
  from .utils import postprocess
  from .utils import layers
  from .utils import losses
  import re
label_desc: Use image node_id 2 for calling the EfficientDetNet obj's underlying member method code with example usage: obj._freeze_vars() and returns: self, unknown