Function operator

docs/app/js/sanddance-app.js:146754–146756

(spec, update)

        return this;
    },
    operator (spec, update) {
        this.add(spec, this.dataflow.add(spec.value, update));
    },
    transform (spec, type) {
        this.add(spec, this.dataflow.add(this.transforms[canonicalType(type)]));
    },