Function optional_seconds 

pub fn optional_seconds(
    config: &HashMap<String, Value>,
    field: &str,
    node_type: &str,
) -> Result<Option<u64>, String>

Parses an optional positive duration in seconds.

Absent means “no duration”; 0 is rejected rather than read as “none”, because the two are too easy to confuse and omitting the field is how you say it. Pure config parsing with no store dependency, so unlike resolve this needs no redis-store-gated pair.