Function expr_chunk_event 

pub fn expr_chunk_event(
    cx: &mut Cx,
    run: Ref,
    seq: u64,
    kind: Symbol,
    expr: Expr,
) -> Result<Event>

Builds a chunk event whose payload is the interned data packet (kind expr).

Used to inject an arbitrary Expr into a run’s event stream at sequence seq under the realize event surface.