Function addFilter

docs/app/js/sanddance-app.js:108045–108047

(a, b)

    return (t)=>map[tupleid(t)] ? null : t;
}
function addFilter(a, b) {
    return a ? (t, i)=>a(t, i) && b(t, i) : b;
}
Pulse.prototype = {
    /**
   * Sentinel value indicating pulse propagation should stop.