class_docstr: Evaluator used for BERT global metrics evaluation.
class_docstr_tok: ["Evaluator","used","for","BERT","global","metrics","evaluation","."]
code: def __len__(self):
      return self._num_examples_added
  
imports: import functools
  from typing import Any, Dict, List, Mapping, Optional, Tuple, Union
  from absl import logging
  from clu import metric_writers
  import flax
  from flax import jax_utils
  import flax.linen
  import jax
  import jax.numpy
  import jax.profiler
  import ml_collections
  import numpy
  from scenic.common_lib import debug_utils
  from scenic.train_lib import optimizers
  from scenic.train_lib import train_utils
  import scipy
  import sklearn.metrics
label_desc: Use image node_id 5 for calling the BERTGlobalEvaluator obj's underlying member method code with example usage: obj.__len__() and returns: self