kb_left_gui is the Windows key on PCs and the Apple key (or Command) on Macs.
kb_left_gui normal some_input
kb_left_control normal some_input
kb_o normal some_input
If necessary, a short delay can be added so the control and gui keys are pressed first:
kb_left_gui normal some_input
kb_left_control normal some_input
kb_o delay_on 100 some_input
gui, control, shift and alt are all "modifiers"; they generally don't do anything on their own, or until they are released. The Windows key does not bring up the start menu until it is released when used by itself, so it can used for command shortcuts, like a control key.