Function read_target 

pub async fn read_target(
    t: &Target,
    contract: Option<&str>,
    src: Sources<'_>,
    out: &Output,
    history: &mut History,
    clock: Clock,
) -> Vec<TargetReading>

Reads and judges one target: one reading per row of Target::rows. Each venue’s market is read once; the token and the address sources once for the target.