Function save 

pub fn save(
    dir: &Path,
    store: &Store,
    name: &str,
    graph: &FlowGraph,
    collection_slug: &str,
    source: Option<TemplateSource>,
) -> Result<TemplateRecord, TemplateError>

Save a template into collection_slug. Membership is written only when the placement is non-default OR a hub source is supplied - keeps the SQLite skinny: in-default user-authored templates have no row.