How to use the haraka-net-utils.is_local_ip function in haraka-net-utils

const part = path_parts[i];

            // while another part remains
            if (i < (path_parts.length - 1)) {
                if (loc[part] === undefined) loc[part] = {};   // initialize
                loc = loc[part];   // descend
                continue;
            }

            // last part, so assign the value
            loc[part] = val;
        }

        // Set is_private, is_local automatically when remote.ip is set
        if (prop_str === 'remote.ip') {
            this.set('remote.is_local', net_utils.is_local_ip(this.remote.ip));
            if (this.remote.is_local) {
                this.set('remote.is_private', true);
            }
            else {
                this.set('remote.is_private', net_utils.is_private_ipv4(this.remote.ip));
            }
        }

        // sunset 3.0.0
        if (prop_str === 'hello.verb') {
            this.greeting = val;
        }
        else if (prop_str === 'tls.enabled') {
            this.using_tls = val;
        }
        else if (prop_str === 'proxy.ip') {