index.js(1,25): error TS7006: Parameter 'f' implicitly has an 'any' type.
index.js(13,29): error TS2345: Argument of type 'IArguments' is not assignable to parameter of type '[f?: any, ...any[]]'.


==== index.js (2 errors) ====
    const format = function(f) {
                            ~
!!! error TS7006: Parameter 'f' implicitly has an 'any' type.
      var str = '';
      var i = 1;
      var args = arguments;
      var len = args.length;
      for (var x = args[i]; i < len; x = args[++i]) {
        str += ' ' + x;
      }
      return str;
    };
    
    const debuglog = function() {
      return format.apply(null, arguments);
                                ~~~~~~~~~
!!! error TS2345: Argument of type 'IArguments' is not assignable to parameter of type '[f?: any, ...any[]]'.
    };
    