CortexGripper Setting property

I have found a bug in the CortexGripper class on line 153

            # Process the command, but clear it as well so future steps are aborted until a new
            # command is sent.
            self.command = None

self.command is a property and as such can not bet set to None if the user provide a speed of None. Commenting the line solves the problem and does not create any additional bug

@nratliff would you please check this

Ah, yeah that’s a bug. Please replace the line self.command = None with self.clear(). This fix will go out with the next release.