docstr: Prunes heads of the model. heads_to_prune: dict of {layer_num: list of heads to prune in this layer}
docstr_tok: ["Prunes","heads","of","the","model",".","heads_to_prune",":","dict","of","{","layer_num",":","list","of","heads","to","prune","in","this","layer","}"]
code: def _prune_heads(self, heads_to_prune):
      """
      Prunes heads of the model. heads_to_prune: dict of {layer_num: list of heads to prune in this layer}
      """
      raise NotImplementedError
  
imports: from dataclasses import dataclass
  from typing import List, Optional, Tuple, Union
  import numpy
  import tensorflow
  from ...activations_tf import get_tf_activation
  from ...modeling_tf_outputs import TFBaseModelOutputWithPastAndCrossAttentions, TFCausalLMOutputWithCrossAttentions, TFSequenceClassifierOutputWithPast
  from ...modeling_tf_utils import TFCausalLanguageModelingLoss, TFConv1D, TFModelInputType, TFPreTrainedModel, TFSequenceClassificationLoss, TFSequenceSummary, TFSharedEmbeddings, get_initializer, keras_serializable, unpack_inputs
  from ...tf_utils import shape_list, stable_softmax
  from ...utils import DUMMY_INPUTS, ModelOutput, add_code_sample_docstrings, add_start_docstrings, add_start_docstrings_to_model_forward, logging, replace_return_docstrings
  from .configuration_gpt2 import GPT2Config
label_desc: Use image node_id 5 for calling the TFGPT2MainLayer obj's underlying member method code with example usage: obj._prune_heads(heads_to_prune) without return types