def enable_thread_safety(self):
        """Enable thread-safety features.

        Must be called before start().

        """
        if self.threadsafe:
            return                        # Already done!
        if self._running.isSet():
            raise RuntimeError('Cannot enable thread safety after start')

        def _getattr(obj, name):
            # use 'is True' so mock objects don't return true for everything
            return getattr(obj, name, False) is True

        for name in dir(self):
            try:
                meth = getattr(self, name)
            except AttributeError:
                # Subclasses may have computed attributes that don't work
                # before they are started, so let's ignore those
                pass
            if not callable(meth):
                continue
            make_threadsafe = _getattr(meth, 'make_threadsafe')
            make_threadsafe_blocking = _getattr(meth, 'make_threadsafe_blocking')

            if make_threadsafe:
                assert not make_threadsafe_blocking
                meth = self._make_threadsafe(meth)
                setattr(self, name, meth)
            elif make_threadsafe_blocking:
                meth = self._make_threadsafe_blocking(meth)
                setattr(self, name, meth)

        self._threadsafe = True
Enable thread-safety features.

        Must be called before start().