anchor.diff:  print(s2.length)
   print(s2.length = 555)
   print(s2.length)
  +print(s2.substr("1",8))
  +print(s2.substring (0, 100))
   .
  
positive.code: 
  (setf (prop string.ctor 'js-user::prototype) string.prototype)
  (setf (prop *global* 'js-user::String) string.ctor)
  
  ;;
  
  
negative.code:      ;;todo: type declarations
       ,@body))
  ;;
  
  (defparameter string.ctor
    (js-function (obj)
  	       (let ((str (if (stringp obj) obj (format nil "~A" obj))))
  