Exactly. The claim is that implicit local variables are less dangerous than implicit global variables. I've been bitten badly by both. Perl was the worst, where implicit variables were scoped differently according to Larry's philosophy when he implemented it. All for the sake of brevity.

Can someone please implement strict mode for Node?

Does that actually run? I don't have an interpreter handy, but the += operator should refer to `smu` before assigning to it, resulting in a NameError.

Actually no:

  >>> for v in (1,2,3):
  ...   smu+=v
  ... 
  Traceback (most recent call last):
    File "<stdin>", line 2, in <module>
  NameError: name 'smu' is not defined