Without arguments, set-time-quantum
prints the time quantum of all cells in the system, as well as the default time quantum (if set).
If the argument is given in cycles the time_quantum attribute is unset. And if the argument is given in seconds then the cpu_switch_time attribute is unset, both in the sim class.
When used in an expression, the command returns the given value, in seconds or cycles, or an exception is raised. Without arguments the current time quantum is returned, or -1 if no cell exists, or if there are cells with different time quantum values.