Function begin_dispatch 

pub fn begin_dispatch(
    node: i64,
    event: &str,
    value: &str,
) -> Option<RuntimeValue>

Simulate an event dispatch on the NATIVE tiers: look up the (node, event) handler, set the current event (its target + value), and hand the closure back to the caller to invoke (the interpreter owns closure invocation). Returns the closure, or None if no handler is registered.