def _remove_untraceable(self):
        """Remove from the tracer those wires that CompiledSimulation cannot track.

        Create _probe_mapping for wires only traceable via probes.
        """
        self._probe_mapping = {}
        wvs = {wv for wv in self.tracer.wires_to_track if self._traceable(wv)}
        self.tracer.wires_to_track = wvs
        self.tracer._wires = {wv.name: wv for wv in wvs}
        self.tracer.trace.__init__(wvs)
Remove from the tracer those wires that CompiledSimulation cannot track.

        Create _probe_mapping for wires only traceable via probes.