Bumper senser

Why do I get left_bumper.pressed() an error name ‘left_bumper’ is not defined?

because left bumper is not defined

either its not named exactly left_bumper or you havent defined it in your devices

Thanks! How do I define it?

Go to the device configuring place where you configure your motor and click add a device. Click three wire and then add the bumper in the right port and name.