Conventional jquery plugin vs AMD jquery plugin

Question

I still can't get my head around with this AMD jquery plugin.

// UMD dance - https://github.com/umdjs/umd
!function(root, factory) {
    if (typeof define === 'function' && define.amd) {
        define(['jquery'], factory);
    } else {
        factory(root.jQuery);
    }
}(this, function($) {
    'use strict';

    // Default options
    var defaults = {

    };

    // Constructor, initialise everything you need here
    var Plugin = function(element, options) {
        this.element   = element;
        this.options   = options;
    };

    // Plugin methods and shared properties
    Plugin.prototype = {
        // Reset constructor - http://goo.gl/EcWdiy
        constructor: Plugin,

        someMethod: function(options) {
            return options;
        }
    };

    // Create the jQuery plugin
    $.fn.plugin = function(options) {
        // Do a deep copy of the options - http://goo.gl/gOSSrg
        options = $.extend(true, {}, defaults, options);

        return this.each(function() {
            var $this = $(this);
            // Create a new instance for each element in the matched jQuery set
            // Also save the instance so it can be accessed later to use methods/properties etc
            // e.g. 
            //    var instance = $('.element').data('plugin');
            //    instance.someMethod();
            $this.data('plugin', new Plugin($this, options));
        });
    };

    // Expose defaults and Constructor (allowing overriding of prototype methods for example)
    $.fn.plugin.defaults = defaults;
    $.fn.plugin.Plugin   = Plugin;
});

Some tests,

console.log($('.some-element').plugin({
        test: 'option1',
        test2: 'option2'
    }));

I always get this empty object,

Object[]

So how can I use this empty object?

And I want to access the method inside the plugin,

    var plugin = $('.element').plugin();
    var instance = $('.element').data('plugin',plugin);
    console.log(instance); // an empty object again!
    console.log(instance.someMethod("hello world"));

TypeError: instance.someMethod is not a function

console.log(instance.someMethod("hello world"));

So how should I do to run the method inside the plugin then?

It is so different from the conventional jquery plugin. AMD's is so difficult to understand. Any idea how I can get this AMD works like the conventional!??

EDIT:

Finally I got something,

    var plugin = $('.element').plugin();
    var instance = $('.element').data('plugin');
    console.log(instance);
    console.log(instance.someMethod("hello world"));

result,

Object { element={...}, options={...}, constructor=function(), more...}

hello world

Why was it so difficult for the those who comment and answer to point this out! Sigh!

Answer 1

    var plugin = $('.element').plugin();
    var instance = $('.element').data('plugin');
    console.log(instance);
    console.log(instance.someMethod("hello world"));

result,

Object { element={...}, options={...}, constructor=function(), more...}

hello world