Function merge_peer_availability 

pub fn merge_peer_availability(
    reports: &BTreeMap<PeerId, PeerAvailability>,
    num_peers: NumPeers,
) -> MergedPeerAvailability

Combines the reports of several guardians into one view.

A peer’s own report about itself is ignored. Of the other reports the NumPeers::one_honest-th lowest value is used, so NumPeers::max_evil lying guardians cannot push a value below every honest report. With at least NumPeers::threshold usable reports they cannot push it above every honest report either. With fewer, for example while a guardian is offline, they can.

For availability, windows whose window_secs does not match PEER_AVAILABILITY_WINDOWS_SECS are ignored, and so are reports that cover less than half of the NumPeers::one_honest-th best coverage. A peer with fewer than NumPeers::one_honest usable reports is omitted.