Add example (#24406)
Add example (#24406)

* Add example

Added an example of how to use is keyword

* Fixed error in syntax highlighting

BhaveshSGupta/FreeCodeCamp,jonathanihm/freeCodeCamp,FreeCodeCamp/FreeCodeCamp,jonathanihm/freeCodeCamp,raisedadead/FreeCodeCamp,BhaveshSGupta/FreeCodeCamp,BhaveshSGupta/FreeCodeCamp,FreeCodeCamp/FreeCodeCamp,raisedadead/FreeCodeCamp