Function held_by_system 

pub fn held_by_system(now: &Now, press: Option<&Press>, here: &str) -> bool

Whether the switch’s mode is held on this device by its own system alone: the switch’s “on”, taken from this device’s own do-not-disturb (here, VIA_SYSTEM), is the only reason for that mode (the pause and Free time have modes of their own). Sioul then adds no mode of its own there: the system’s cause silences the device already, and a mode of Sioul’s would hide its end (Android shows an application only the effective state).