'Convert into datetime.datetime'

@staticmethod
def _datetime(b):

    if isinstance(b, datetime.datetime):
        return b
    elif isinstance(b, basestring):
        dt = None
        try:
            (y, m, d, hh, mm, ss, t0, t1, t2) = time.strptime(b, ISOFORMAT)
        except ValueError:
            dt = b
        else:
            dt = datetime.datetime(y, m, d, hh, mm, ss)
        from s3validators import IS_UTC_DATETIME
        (dt, error) = IS_UTC_DATETIME()(dt)
        if error:
            try:
                dt = s3_decode_iso_datetime(b)
            except:
                raise ValueError
            else:
                (dt, error) = IS_UTC_DATETIME()(dt)
        return dt
    else:
        raise TypeError
