code: function (name, prop) {
  		this.unsetProperty(name);
  		this.properties[name] = prop;
  		this.listenTo(prop, EVENT_CHANGE, this.change);
  		return prop;
  	}
docs: Set a single property to a new value
  @param {string} name Property name
  @param {module:ok.Property} prop Property object
  @return {module:ok.Property} The new property