Describes a worker, which is a list of one of more devices and the connextions between them. A device could be a computer, a phone or a GPU.
The first device is known as the Primary Device which is responsible for executing commands. All other devices are known as Attatched Devices and must be controlled by the Primary Device.
Adds a class:Device to this instance. First device added should be the Primary Device.
Returns the protobuffer representation of a