text: //// [multiCallOverloads.ts]
  interface ICallback {
      (x?: string):void;
  }
  
  function load(f: ICallback) {}
  
  var f1: ICallback = function(z?) {}
  var f2: ICallback = function(z?) {}
  load(f1) // ok
  load(f2) // ok
  load(function() {}) // this shouldn’t be an error
  load(function(z?) {}) // this shouldn't be an error
  
  
  //// [multiCallOverloads.js]
  function load(f) {
  }
  
  var f1 = function (z) {
  };
  var f2 = function (z) {
  };
  load(f1); // ok
  load(f2); // ok
  load(function () {
  }); // this shouldn’t be an error
  load(function (z) {
  }); // this shouldn't be an error
  