code: def _decode_blob_key(key):
      """Decode a blob key produced by `_encode_blob_key` into component fields.
  
      Args:
        key: a blob key, as generated by `_encode_blob_key`.
  
      Returns:
        A tuple of `(experiment_id, plugin_name, run, tag, step, index)`, with types
        matching the arguments of `_encode_blob_key`.
      """
      decoded = base64.urlsafe_b64decode(
          key + "=="
      )  # pad past a multiple of 4.
      stringified = decoded.decode("ascii")
      (experiment_id, plugin_name, run, tag, step, index) = json.loads(
          stringified
      )
      return (experiment_id, plugin_name, run, tag, step, index)
  
imports: import base64
  import collections
  import json
  import random
  from tensorboard import errors
  from tensorboard.compat.proto import summary_pb2
  from tensorboard.data import provider
  from tensorboard.util import tb_logging
  from tensorboard.util import tensor_util
label_desc: Use image node_id 2 for calling a global function with example usage: _decode_blob_key(key) and returns: experiment_id,  plugin_name,  run,  tag,  step,  index