'Gets a DateTime object for the decade year.
:param before_now: include days in current decade before today
:param after_now: include days in current decade after today
:param tzinfo: timezone, instance of datetime.tzinfo subclass
:example DateTime(\'2012-04-04 11:02:02\')
:return DateTime'

@classmethod
def date_time_this_decade(cls, before_now=True, after_now=False, tzinfo=None):

    now = datetime.now(tzinfo)
    this_decade_start = datetime((now.year - (now.year % 10)), 1, 1, tzinfo=tzinfo)
    next_decade_start = datetime((this_decade_start.year + 10), 1, 1, tzinfo=tzinfo)
    if (before_now and after_now):
        return cls.date_time_between_dates(this_decade_start, next_decade_start, tzinfo)
    elif ((not before_now) and after_now):
        return cls.date_time_between_dates(now, next_decade_start, tzinfo)
    elif ((not after_now) and before_now):
        return cls.date_time_between_dates(this_decade_start, now, tzinfo)
    else:
        return now
