code: def _parse_alerts_blob_key(blob_key):
      """Parse the BLOB key for Alerts.
  
      Args:
        blob_key: The BLOB key to parse. By contract, it should have the format:
         - `${ALERTS_BLOB_TAG_PREFIX}_${begin}_${end}.${run_id}` when there is no
           alert type filter.
         - `${ALERTS_BLOB_TAG_PREFIX}_${begin}_${end}_${alert_filter}.${run_id}`
           when there is an alert type filter.
  
      Returns:
        - run ID
        - begin index
        - end index
        - alert_type: alert type string used to filter retrieved alert data.
            `None` if no filtering is used.
      """
      key_body, run = blob_key.split(".", 1)
      key_body = key_body[len(ALERTS_BLOB_TAG_PREFIX) :]
      key_items = key_body.split("_", 3)
      begin = int(key_items[1])
      end = int(key_items[2])
      alert_type = None
      if len(key_items) > 3:
          alert_type = key_items[3]
      return run, begin, end, alert_type
  
imports: import json
  from tensorboard.data import provider
  from tensorboard.plugins.debugger_v2 import debug_data_multiplexer
label_desc: Use image node_id 2 for calling a global function with example usage: _parse_alerts_blob_key(blob_key) and returns: run,  begin,  end,  alert_type