//   used at 8:12, 8:17
	// type string:
	//   defined at -
	//   used at 4:8
	// var b S:
	//   defined at fib:6:8
	//   used at 6:19
	// var c string:
	//   defined at fib:6:11
	//   used at 6:25
	// var x int:
	//   defined at fib:8:10
	//   used at 10:10, 12:13, 12:24, 9:5
	//
	// Types and Values of each expression:
	//  4: 8 | string              | type    : string