code: def _convert_time(date_str, time_str):
      """Convert date and time strings to float time."""
      if date_str == time_str == "":
          date_str = "01/01/1970"
          time_str = "00:00:00"
          logger.info(
              "No date or time found, setting to the start of the "
              "POSIX epoch (1970/01/01 midnight)"
          )
  
      for fmt in ("%d/%m/%Y", "%d-%b-%Y", "%a, %b %d, %Y", "%Y/%m/%d"):
          try:
              date = strptime(date_str.strip(), fmt)
          except ValueError:
              pass
          else:
              break
      else:
          raise RuntimeError(
              "Illegal date: %s.\nIf the language of the date does not "
              "correspond to your local machine's language try to set the "
              "locale to the language of the date string:\n"
              'locale.setlocale(locale.LC_ALL, "en_US")' % date_str
          )
  
      for fmt in ("%H:%M:%S", "%H:%M"):
          try:
              time = strptime(time_str, fmt)
          except ValueError:
              pass
          else:
              break
      else:
          raise RuntimeError("Illegal time: %s" % time_str)
      # MNE-C uses mktime which uses local time, but here we instead decouple
      # conversion location from the process, and instead assume that the
      # acquisition was in GMT. This will be wrong for most sites, but at least
      # the value we obtain here won't depend on the geographical location
      # that the file was converted.
      res = timegm(
          (
              date.tm_year,
              date.tm_mon,
              date.tm_mday,
              time.tm_hour,
              time.tm_min,
              time.tm_sec,
              date.tm_wday,
              date.tm_yday,
              date.tm_isdst,
          )
      )
      return res
  
imports: import os.path
  from calendar import timegm
  from time import strptime
  import numpy
  from ..._fiff.constants import FIFF
  from ..._fiff.ctf_comp import _add_kind, _calibrate_comp
  from ..._fiff.meas_info import _empty_info
  from ..._fiff.write import get_new_file_id
  from ...annotations import Annotations
  from ...transforms import _coord_frame_name, apply_trans, combine_transforms, invert_transform
  from ...utils import _clean_names, logger, warn
  from .constants import CTF
label_desc: Use image node_id 2 for calling a global function with example usage: _convert_time(date_str, time_str) and returns: res