code: function(source, target, key) {
  		var desc = Object.getOwnPropertyDescriptor(source, key);
  		desc = this._accessor(target, key, desc);
  		Object.defineProperty(target, key, desc);
  		return target;
  	}
docs: Copy property from source to target. Main feature is that it
  will be setup to a property accessor (getter/setter) provided:
  
  1) The property value is an object
  2) It has (only) one or both properties "getter" and "setter"
  3) These are both functions