A delay tree is a superset of a nodal tree (see (container nodal-tree)). It
extends nodal trees to allow any entry of the node to be a promise created with
the delay operator.
5.2 Usage
— Function: force-ref node field
Access a field in a node of a delay tree. If the value of the field is a
promise, the promise will be forced, and the value will be replaced with the
forced value.