interface SearchFunc {
  (source: string, subString: string): boolean;
}
var mySearch: SearchFunc;
mySearch = function(source: string, subString: string) {
  var result = source.search(subString);
  if (result == -1) {
    return false;
  }
  else {
    return true;
  }
}
class Greeter {
    greeting: string;
    constructor(message: string) {
        this.greeting = message;
    }
    greet() {
        return "Hello, " + this.greeting;
    }
}
var greeter = new Greeter("world");