code: def time_to_hhmmssmmm(time_value, decimal_separator="."):
      
      if time_value is None:
          time_value = 0
      tmp = time_value
      hours = int(math.floor(tmp / 3600))
      tmp -= (hours * 3600)
      minutes = int(math.floor(tmp / 60))
      tmp -= minutes * 60
      seconds = int(math.floor(tmp))
      tmp -= seconds
      milliseconds = int(math.floor(tmp * 1000))
      return "%02d:%02d:%02d%s%03d" % (
          hours,
          minutes,
          seconds,
          decimal_separator,
          milliseconds
      )
docs: Format the given time value into a ``HH:MM:SS.mmm`` string.
  
      Examples: ::
  
          12        => 00:00:12.000
          12.345    => 00:00:12.345
          12.345432 => 00:00:12.345
          12.345678 => 00:00:12.346
          83        => 00:01:23.000
          83.456    => 00:01:23.456
          83.456789 => 00:01:23.456
          3600      => 01:00:00.000
          3612.345  => 01:00:12.345
  
      :param float time_value: a time value, in seconds
      :param string decimal_separator: the decimal separator, default ``.``
      :rtype: string