code: def extract_version(metadata):
      """Extracts version from invocation metadata.
  
      The argument should be the result of a prior call to `metadata` or the
      result of combining such a result with other metadata.
  
      Returns:
        The TensorBoard version listed in this metadata, or `None` if none
        is listed.
      """
      return dict(metadata).get(_VERSION_METADATA_KEY)
  
imports: import enum
  import functools
  import random
  import threading
  import time
  import grpc
  from tensorboard import version
  from tensorboard.util import tb_logging
label_desc: Use image node_id 5 for calling a global function with example usage: extract_version(metadata) and returns: dict