'Get all the identity information that has been received and
are still valid about the subject.
:param subject_id: The identifier of the subject
:param entities: The identifiers of the entities whoes assertions are
interesting. If the list is empty all entities are interesting.
:return: A 2-tuple consisting of the identity information (a
dictionary of attributes and values) and the list of entities
whoes information has timed out.'

def get_identity(self, subject_id, entities=None, check_not_on_or_after=True):

    res = {}
    oldees = []
    if (not entities):
        for item in self._cache.find({'subject_id': subject_id}):
            try:
                info = self._get_info(item, check_not_on_or_after)
            except ToOld:
                oldees.append(item['entity_id'])
                continue
            for (key, vals) in info['ava'].items():
                try:
                    tmp = set(res[key]).union(set(vals))
                    res[key] = list(tmp)
                except KeyError:
                    res[key] = vals
    else:
        for entity_id in entities:
            try:
                info = self.get(subject_id, entity_id, check_not_on_or_after)
            except ToOld:
                oldees.append(entity_id)
                continue
            for (key, vals) in info['ava'].items():
                try:
                    tmp = set(res[key]).union(set(vals))
                    res[key] = list(tmp)
                except KeyError:
                    res[key] = vals
    return (res, oldees)
