code: def time_msecs_str(t: Union[int, float]) -> str:
      return datetime.datetime.utcfromtimestamp(t / 1000).strftime(
          "%Y-%m-%dT%H:%M:%SZ"
      )
  
file_path: hail/hail/python/hailtop/utils/time.py
imports: import time
  from typing import Optional, overload, Union
  import datetime
  import dateutil.parser
  from ..humanizex import naturaldelta_msec
label_desc: Use image node_id 3 for calling a global function with example usage: time_msecs_str(t) and returns: datetime