def add(intr):
    """ Add the IIntrospectable ``intr`` (use instead of
        :meth:`pyramid.interfaces.IIntrospector.add` when you have a custom
        IIntrospectable). Replaces any existing introspectable registered
        using the same category/discriminator.

        This method is not typically called directly, instead it's called
        indirectly by :meth:`pyramid.interfaces.IIntrospector.register`"""
