code: function cancelize(fn) {
    return function cancelized() {
      if (!arguments.length) {
        throw new Error('cancelized: expected at least one argument');
      }
      var args = Array.prototype.slice.call(arguments, 0);
      var done = args[args.length - 1] = once(args[args.length - 1]);
  
      function cancel() {
        done.apply(null, arguments);
      }
  
      fn.apply(null, args);
  
      return cancel;
    };
  }
docs: Wrap a non-cancellable asynchronous function into a cancelable one.  Calling cancel() on the returned function will not interrupt the execution of the original function; it will merely ignore its return value.  Usually, instead of wrapping your function, you want to implement cancel() yourself in order to have some abort logic. This utility function provides a straighforward solution for cases in which no custom abort logic is required.