docs: function observe (value) {
  	  if (!isObject(value)) {
  	    return
  	  }
  	  var ob;
  	  if (hasOwn(value, '__ob__') && value.__ob__ instanceof Observer) {
  	    ob = value.__ob__;
  	  } else if (
  	    observerState.shouldConvert &&
  	    !config._isServer &&
  	    (Array.isArray(value) || isPlainObject(value)) &&
  	    Object.isExtensible(value) &&
  	    !value._isVue
  	  ) {
  	    ob = new Observer(value);
  	  }
  	  return ob
  	}