Function metered 

fn metered() -> bool

The connection is metered (NetworkManager: yes, or guessed yes), as the system’s reading thread last read it (devices::watch_system, every thirty seconds): never asked here, so that an exchange never waits on the system’s bus (review of battery part C, G1). Before this process’s first reading (the window’s first exchange, a moment after its start), that reading is waited for FIRST_READING at most, once, and none come by then, the connection counts as metered: a phone’s hotspot is not spent on a full round at each start (L3). Read once, a reading too old to keep says nothing: not metered. On a phone, not known here (measured instead: Sending::slow).