docstr: Parse the event file in the given path and return the
  only summary value.
docstr_tok: ["Parse","the","event","file","in","the","given","path","and","return","the","only","summary","value","."]
code: def parse_and_return_summary_value(self, path):
      """Parse the event file in the given path and return the
      only summary value."""
      event_value_list = []
      event_file_generator = directory_watcher.DirectoryWatcher(
          path, event_file_loader.EventFileLoader
      ).Load()
      event_values = itertools.chain.from_iterable(
          map(_process_event, event_file_generator)
      )
      for value_dict in event_values:
          event_value_list.append(value_dict)
  
      self.assertLen(event_value_list, 1)
      self.assertEqual(event_value_list[0]["step"], 1)
      self.assertGreater(event_value_list[0]["wall_time"], 0.0)
      return event_value_list[0]["value"]
  
imports: import itertools
  import pathlib
  import tempfile
  import numpy
  import tensorflow
  from absl.testing import absltest
  from tensorboard.backend.event_processing import directory_watcher, event_file_loader
  from tensorboard.util import tensor_util
  from flax.metrics.tensorboard import SummaryWriter, _flatten_dict
label_desc: Use image node_id 1 for calling the TensorboardTest obj's underlying member method code with example usage: obj.parse_and_return_summary_value(path) and returns: event_value_list