'Given a list of file info dicts, reverse sorted by timestamp, split the
list into two: items newer than or at same time as the timestamp, and
items older than timestamp.
:param file_info_list: a list of file_info dicts.
:param timestamp: a Timestamp.
:return: a tuple of two lists.'

def _split_gte_timestamp(self, file_info_list, timestamp):

    return self._split_list(file_info_list, (lambda x: (x['timestamp'] >= timestamp)))
