docs: def expire_data(self):
          """Expire data within the samples collection."""
  
          # Do we need to start deleting stuff?
          while self.sample_storage_size() > self.samples_cap:
  
              # This should return the 'oldest' record in samples
              record = self.database[self.sample_collection].find().sort('import_time',pymongo.ASCENDING).limit(1)[0]
              self.remove_sample(record['md5'])