pub const PARALLEL: &str = "parallel";Expand description
parallel: block — a scope whose bindings are its children.
The scope is a form, for the same reason TRY is: a handler that owns its children has
to own them lexically, and a nursery whose membership were decided at run time would be a
dynamic search with the same objection (docs/38
§38.4). Both halves of §38.4’s shape are here — the children are the scope’s lets, and
there is no handle for one to escape in.