Tips for NightShift Nurses

 The Codes for the light machine in the basement are as follow:

              o  =on                levers #1-4 from top to bottom
              *  =off


Key        1 | 2 | 3 | 4
~~~~~~~~~~~~~~~~~~~~~~~~~
Key 1      o | * | o | *
 
Key 2      * | o | o | o

Key 3      o | o | * | o

Key 4      o | * | * | o