docs: def datetime_to_jd(date):
      """
      Convert a `datetime.datetime` object to Julian Day.
  
      Parameters
      ----------
      date : `datetime.datetime` instance
  
      Returns
      -------
      jd : float
          Julian day.
  
      Examples
      --------
      >>> d = datetime.datetime(1985,2,17,6)  
      >>> d
      datetime.datetime(1985, 2, 17, 6, 0)
      >>> jdutil.datetime_to_jd(d)
      2446113.75
  
      """
      days = date.day + hmsm_to_days(date.hour,date.minute,date.second,date.microsecond)
  
      return date_to_jd(date.year,date.month,days)