Do not use instance of dict() as default for seen

Classic mistake:

  def foo(arg={}):
    …

this will instantiate a dict and use *the same instance* on subsequent
invocations, i.e. as if you used foo.arg inside the function.

Instead, instantiate the dict() in the function body!

Signed-off-by: martin f. krafft <madduck@madduck.net>
1 file changed