Raise an exception when we cannot connect to device.
Ues a reentrant lock around the conn. so we can lock twice in a thread.
Document how we handle async noti/indications.
Handle multibyte payloads in notifications.
Pull async notificaiton expectations to a function.
Combine to characterstic write functions into one.
Handle callbacks a thread separate from pexpect.
Increase timeouts for most BLE responses.
Print when command is sent so we can gauge the time.