Implemented `switch_register`.
Implemented `switch_register`.

This fixes two of the test failures from the last commit.

henn/hil_sahil,lokI8/haas,apoorvemohan/haas,henn/hil,kylehogan/hil,SahilTikale/haas,henn/hil,kylehogan/hil,SahilTikale/switchHaaS,CCI-MOC/haas,kylehogan/haas,henn/hil_sahil,meng-sun/hil,henn/haas,meng-sun/hil,apoorvemohan/haas