Function map 

pub fn map<F>(
    core: &Core,
    binding: &Arc<dyn OperatorBinding>,
    source: NodeId,
    project: F,
) -> OperatorRegistration
where
    F: Fn(HandleId) -> HandleId + Send + Sync + 'static,

map(source, project) — element-wise transform.

Maps each settled value from source through project. Each input in a wave’s batch produces one output (R5.7 batch-mapping).

Example

let mapped = map(core, binding, source, |h: HandleId| h);