I didn't mean that the ``threshold`` function wouldn't be public, just the module it's in now. If you look at the scipy module hierarchy you'll see it is very flat: https://github.com/scipy/scipy/blob/master/doc/API.rst.txt

So this function will be exposed as one of (in decreasing order of likelihood):

    signal.wavelets.threshold
    signal.threshold
    wavelets.threshold

All new non-public Python files will have underscores prepended to their names, in order to ensure people won't start to import from them.