'Return an iterable of model.Sample instances.
:param sample_filter: Filter.
:param limit: Maximum number of results to return.'

def get_samples(self, sample_filter, limit=None):

    if (limit == 0):
        return []
    q = pymongo_utils.make_query_from_filter(sample_filter, require_meter=False)
    return self._retrieve_samples(q, [('timestamp', pymongo.DESCENDING)], limit)
