sin.js

function expandAllRefs(
  rootDoc,
  currentValue = rootDoc,
  update = cannotUpdateRootNode
) {
  // This is definitely a sin
  // Boy, I would hate to find out the performance of this in deeply nested code
  for (const key of Object.keys(currentValue)) {
    const value = currentValue[key];

    if (isRef(key)) {
      update(expandRef(rootDoc, value));
      continue;
    }

    // We do not attempt to resolve values for non-objects.
    if (typeof value !== "object") {
      continue;
    }

    const nextUpdate = nextValue => {
      currentValue[key] = nextValue;
    };

    return expandAllRefs(rootDoc, value, nextUpdate);
  }

  return rootDoc;
}