Function
purge-surrogate-key-verbose
Purge a surrogate key for the current service, and return the purge id.
This is similar to purge-surrogate-key, but on success, returns a
JSON purge response containing an ASCII alphanumeric string identifying
a purging.
purge-surrogate-key-verbose: func(surrogate-keys: string, purge-options: purge-options, max-len: u64) -> result<string, error>;