src/promissory-arbiter.js
function applyTopicDescendents (f, property, topic, topics) {
    var node = ancestorTopicSearch(topic, topics);
    if (node.topic === topic) {
      return curryMap(property, f, descendents(node));
    }

    return null;
  }
function applyTopicDescendents (f, property, topic, topics) {
    var node = ancestorTopicSearch(topic, topics);
    if (node.topic === topic) {
      return curryMap(property, f, descendents(node));
    }

    return null;
  }
function applyTopicDescendents ( f , property , topic , topics ) { var node = ancestorTopicSearch ( topic , topics ) ; if ( node . topic === topic ) { return curryMap ( property , f , descendents ( node ) ) ; } return null ; }
For all descendants of `topic` remove all elements of `node[property`.
For all descendants of topic remove all elements of node [ property .