unknown-property.js

unknownProperty: function(key) {
  var namespacedKey = this._key(key);
  var payload = this.get('persistence').getItem(namespacedKey);
  return this._deserialize(payload);
},

_deserialize: function(value) {
  return JSON.parse(value);
},

_key: function(key) {
  return "%@:%@".fmt(this.get('namespace'), key);
},

// ...