code: def timestamp_query_str(
      start_time: str, end_time: Optional[str]
  ) -> str:
      timestamp_query = f";startTime={start_time}"
      if end_time is not None:
          timestamp_query += f";endTime={end_time}"
      return timestamp_query
  
file_path: hail/ci/ci/utils.py
imports: import datetime
  import secrets
  import string
  import urllib.parse
  from typing import List, Optional
  from gear import Database
  from gear.cloud_config import get_gcp_config
label_desc: Use image node_id 3 for calling a global function with example usage: timestamp_query_str(start_time, end_time) and returns: timestamp_query