Function report 

pub fn report(
    host: &str,
    since: Option<&str>,
    deployments: &[Deployment],
    lookup: &dyn Fn(&Deployment) -> Option<Vec<Exposed>>,
    current: &dyn Fn(&str) -> Option<CurrentEntry>,
) -> Report

Builds the report. deployments are what the host received, lookup maps a file hash to what it contained (None = not recorded), current maps an entry id to what the vault holds now (None = deleted).