code: def get_time_string(time_gmt=None):
      
      if isinstance(time_gmt, datetime.datetime):
          time_gmt = time_gmt.timetuple()
      if time_gmt is None:
          time_gmt = time.gmtime()
      if isinstance(time_gmt, time.struct_time):
          return time.strftime(API_FORMAT, time_gmt)
      raise TypeError("time_gmt must be a time_struct, datetime, or None. A %s "
                      "was passed." % type(time_gmt))
docs: The canonical time string format (in UTC).
  
      :keyword time_gmt: this is a time_struct, datetime class, or None. If None,
          the current time is used. Its name, time_gmt, is for legacy support for
          functions that called it before it supported multiple values.
  
      Changing this function will change all times that projects using simpl
          return in their APIs.