human
Solve the following python programming problem given the following code:
def _setup_get_all_vdi_uuids_for_vm(self, vm_get_vbd_refs, vbd_get_rec, vdi_get_uuid) : 
    def fake_vbd_get_rec(session, vbd_ref) : 
        return { 
            'userdevice' : vbd_ref, 
            'VDI' : ('vdi_ref_%s' % vbd_ref), 
} 
def fake_vdi_get_uuid(session, vdi_ref) : 
        return vdi_ref 
vm_get_vbd_refs.return_value = ['0', '2'] 
    vbd_get_rec.side_effect = fake_vbd_get_rec 
    vdi_get_uuid.side_effect = <MASK> 
    
    Given the code above, what is a proper replacement for <MASK>?
assistant
#Here is a proper replacement for <MASK>.
def fake_vdi_get_uuid(