prefix: Prefix for keys. We'll generate a number of keys that start with this string. Probably terminating the string with a punctuation character (e.g., ":") will make created strings nicer to deal with.
con: A redis_api connection object, as created by redux. Alternatively if passing in a redis_config
object, a list, or NULL this will be passed through to hiredis to create a new connection.
hash_algorithm: Name of the hash algorithm to use. Possible values are "md5", "sha1", and others supported by digest. If not given, then we will default to "md5".