'Given a unix time, return a LogReader for an old log file.'

def getLog(self, identifier):

    if (self.toDate(identifier) == self.lastDate):
        return self.getCurrentLog()
    filename = ('%s.%s' % (self.path, self.suffix(identifier)))
    if (not os.path.exists(filename)):
        raise ValueError('no    such    logfile    exists')
    return LogReader(filename)
