an object called by this method can not have any new properties being added. but it can change existing property values as long as writable metadata is true.
a stateful widget is a dynamic widget which can change the appearance of its content in response toevents triggered by user's interactions or when it receives data.
Experimental support for decorators is a feature that is subject to change in a future release. Set the 'experimentalDecorators' option in your 'tsconfig' or 'jsconfig' to remove this warning