code: def get_s3store_instance(bucket):
      
      global _s3store_instances
  
      key = "%s" % bucket
  
      try:
          instance = _s3store_instances[key]
      except KeyError:
          instance = S3Store(
              bucket=bucket
          )
          _s3store_instances[key] = instance
  
      return instance
docs: Return an instance of S3Store.