function EventTarget() {
    this._listeners = {};
}

EventTarget.prototype = {

    constructor: EventTarget,

    addListener: function (type, listener) {
        if (typeof this._listeners[type] == "undefined") {
            this._listeners[type] = [];
        }

        this._listeners[type].push(listener);
    },

    fire: function (event) {
        if (typeof event == "string") {
            event = { type: event };
        }
        if (!event.target) {
            event.target = this;
        }

        if (!event.type) {  //falsy
            throw new Error("Event object missing 'type' property.");
        }

        if (this._listeners[event.type] instanceof Array) {
            var listeners = this._listeners[event.type];
            for (var i = 0, len = listeners.length; i < len; i++) {
                listeners[i].call(this, event);
            }
        }
    },

    removeListener: function (type, listener) {
        if (this._listeners[type] instanceof Array) {
            var listeners = this._listeners[type];
            for (var i = 0, len = listeners.length; i < len; i++) {
                if (listeners[i] === listener) {
                    listeners.splice(i, 1);
                    break;
                }
            }
        }
    }
};