code: def deleteUnused(self):
          
          (count, size) = (0, 0)
  
          for (diff, path) in self.extraKeys.items():
              if path.startswith("/"):
                  continue
  
              keyName = self._keyName(diff.toUUID, diff.fromUUID, path)
  
              count += 1
              size += diff.size
  
              if self._skipDryRun(logger, 'INFO')("Trash: %s", diff):
                  continue
  
              try:
                  self.bucket.copy_key(theTrashPrefix + keyName, self.bucket.name, keyName)
                  self.bucket.delete_key(keyName)
              except boto.exception.S3ResponseError as error:
                  logger.error("%s: %s", error.code, error.message)
  
              try:
                  keyName = os.path.dirname(keyName) + Store.theInfoExtension
                  self.bucket.copy_key(theTrashPrefix + keyName, self.bucket.name, keyName)
                  self.bucket.delete_key(keyName)
              except boto.exception.S3ResponseError as error:
                  logger.debug("%s: %s", error.code, error.message)
  
          logger.info("Trashed %d diffs (%s)", count, humanize(size))
docs: Delete any old snapshots in path, if not kept.