docs: function Dispatcher(emitter, events) {
    if (!(this instanceof Dispatcher)) return new Dispatcher(emitter, events);
  
    assert(emitter instanceof EventEmitter, 'simple-dispatcher: emitter should be an EventEmitter');
    assert('object' == typeof events, 'simple-dispatcher: events should be an object');
  
    // iterate over keys in event
    // and map the cb values to the emitter.
  
    Object.keys(events).forEach(function(key) {
      var arr = Array.isArray(events[key]) ? events[key] : [events[key]];
      arr.forEach(function(cb) {
        emitter.on(key, cb);
      });
    });
  }