code: function reassignJavadoc(from, to) {
    if (!(from.doc instanceof Javadoc)) {
      // Nothing to transfer.
      return from;
    }
    to.doc = from.doc;
    delete from.doc;
    return Object.keys(from).length === 1 ? from.type : from;
  }
docs: Transfer a key from an object to another and return the new source.
  
  If the source becomes an object with a single type attribute set, its `type`
  attribute is returned instead.