19         let cb = function () { }; // start with noop.  function
21             cb = args.pop();
22         cb = cb || function () { }; // noop.
34                 cb  property
38             cb();
47         let cb = function () { }; // start with noop.  function
49             cb = args.pop();
69                 cb  property
73             cb();
119         const cb = work.cb;
126             cb(err);