4. The method of claim 1 , wherein the first client device and the second client device are paired.
4. The method of claim 1 , wherein the first client device and the second client device are paired. 5. The method of claim 4 , comprising: performing a process to pair the first client device and the second client device, the process comprising: transmitting, from the first client device and for receipt by the second client device, information identifying the first client device, and receiving, by the first client device and from the second client device, information identifying the second client device.