code: function functionBind(f, obj) {
    if (NATIVE_FUNCTION_BIND) {
      return NATIVE_FUNCTION_BIND.call(f, obj);
    }
  
    return function boundFunction_() {
      return f.apply(obj, arguments);
    };
  }
docs: Bind a function's 'this' value.
  @param {function} f The function.
  @param {object} obj The object.
  @return {function} The bound function.