text: interface point = {
  	readonly x : number,
  	readonly y : number
  }
  
  let p1 : point = { x:8, y:9};
  p1.x = 10  // throw error
  
  
  
  interface person = {
  	firstName : string,
  	lastName : string,
  	age?: number. // option field
  }
  
  var mickel:person = {
  	firstName : "mic",
  	lastName : "dsoza"
  }
  