code: function (changeset) {
  					changeset.forEach(function(change) {
  						if(change.name!=="__target__") {
  							if(change.type==="delete") {
  								delete proxy[change.name];
  							} else if(change.type==="update") { // update handler if target key value changes from function to non-function or from a non-function to a function
  								if((typeof(change.oldValue)==="function" && typeof(target[change.name])!=="function") || (typeof(change.oldValue)!=="function" && typeof(target[change.name])==="function")) {
  									addHandling(proxy,change.name,target[change.name]);
  								}
  							} else if(!proxy[change.name]) {
  								addHandling(proxy,change.name,target[change.name]);
  							}
  						}
  					})}
docs: Observe the target for changes and update the handlers accordingly