var subject = require('subject');

// define person builder
var person = subject.define({

        // This will be called on instantiation
        initialize: function (data) {
            this.name = data.name;
        },

        // These are simple methods and prototype properties.
        introduceSelf: function () {
            return 'My name is ' + this.name
        },

        walk: function () {
            // 
        }
    });

// instantiate person
var joe = person({ name: 'Joe Smith' });

joe.introduceSelf() // My name is Joe Smith


// define musician builder, which should inherit from person
var musician = person.define({
        // Overwrite initialization
        initialize: function (data) {
            // call the person's
            person.base.initialize.apply(this, arguments);

            this.instruments = data.instrments;
        },

        play: function (instrument) {
            return _.contains(this.instruments, instrument) ? '♬ ♫ ♪ ♩ ♭ La La La' : 'I can\'t play that!';
        }
    });

// instantiate musician
var bob = musician({ name: 'Bob Dylan', instruments: ['guitar', 'voice', 'harmonica'] });

// person methods
bob.introduceSelf()    // My name is Bob Dylan

// musician methods.
bob.play('harmonica')  // ♬ ♫ ♪ ♩ ♭ La La La
bob.play('trumpet')    // I can't play that!