{question: answerNode, statement: commentNode}
{retry: [nodeA, nodeB]} // fan-out: both triggered
JavaScript object keys are always strings, so a numeric key ({2: node}) and
a boolean key ({true: node}) are reconstructed to their typed
RouteValue (2, true) when parsed — mirroring Python dict keys.
Because of this, routes are matched by string value
(Graph.getNextPendingNodes compares String(route) on both sides), so
a node emitting 2 and one emitting '2' both fire a {2: node} edge. The
flip side is that a numeric/boolean-looking route and its string spelling
cannot be distinguished in a routing map; use distinct, non-ambiguous route
keys when that matters.
A mapping from route values to destination node(s). A value may be a single node or an array of nodes (fan-out).