n4ds_abi_version        The C ABI version string.
n4ds_fetch              Download + SHA-256-verify a resolved dataset
                        into the cache (JSON status string).
n4ds_resolve            Resolve a dataset id against an index JSON into
                        its download contract (JSON string).
n4ds_verify_cached      Re-verify a cached dataset directory against
                        the contract's SHA-256s (JSON report).
