Taking separate date and time strings (which are not following a specific format), turn them into datetime objects and return [start, end]

dates.py

def event_dates(date, time):
    """Takes the event's date and time fields,
       returns a start date and end date (if applicable)
       example date: "2017/09/16 00:00:00 GMT-4"
       example time: "11:00 am" or "9:00am - 11:00pm"
    """
    if not date:
        return [None, None]
    date = date.replace('GMT-4', 'America/New_York')
    if not time:
        return [date, date]
    time_no_dots = time.replace('.', '').replace('–', '-')
    evtime = time_no_dots.lower().split('-')
    start_end = []
    for item in evtime:
        am_or_pm = 'am'  # default to am if not specified
        if 'am' in item:
            item = item.replace('am', '')
        elif 'pm' in item or 'pm' in time_no_dots:
            am_or_pm = 'pm'
            item = item.replace('pm', '')
        if 'noon' in item.lower():
            am_or_pm = 'pm'
            item = '12:00'

        units = item.strip().split(':')
        if am_or_pm == 'pm':
            try:
                if units[0] != '12':
                    units[0] = str(int(units[0].split(' ')[0]) + 12)
            except ValueError:
                start_end.append(date)
                continue
        if len(units) == 1:
            new_time = ':'.join(units) + ':00'
        else:
            new_time = ':'.join(units)
        try:
            datetime.strptime(new_time, '%H:%M')
            start_end.append(date.replace('00:00:00', new_time))
        except ValueError:
            start_end.append(date)
    if len(start_end) == 1:
        start_end.append(None)
    return start_end