Implement Device.__eq__()

[martijnthe]

I'd like to be able to write something like:

devs = set()
devs |= set(usb.core.find(find_all=True, custom_match=matcher_one))
devs |= set(usb.core.find(find_all=True, custom_match=matcher_two))

If matcher_one and matcher_two both match device XYZ, devs will contain two instances of Device referring to XYZ. I'd expect devs to contain only one instance referring to XYZ.

[jonasmalacofilho]

Thoughts on implementing __eq__ as follows?

def __eq__(self, other):
    return (self.backend, self.bus, self.address) == \
           (other.backend, other.bus, other.address)

Essentially defining equality based on the OS's view of the USB tree, but also taking into account the different possible backends.

Cc: @mcuee

[mcuee]

Looks good to me.