Python timestamp

timestamp.py

def date_from_timestamp_ms(timestamp_ms):
    date = datetime.utcfromtimestamp(timestamp_ms / 1000.0)
    return date


def format_date(timestamp_ms, sep=None):
    if sep is None:
        sep = '_'
    date = date_from_timestamp_ms(timestamp_ms)
    return date.strftime('%Y{0}%m{0}%d'.format(sep))


def parse_date(datestr, sep=None):
    if sep is None:
        sep = '_'
    date = datetime.strptime(datestr, '%Y{0}%m{0}%d'.format(sep))
    timestamp_ms = int(calendar.timegm(date.timetuple()) * 1000.0)