code: public DBObject parse(UNode docNode) {
          Utils.require(docNode != null, "docNode");
          Utils.require(docNode.getName().equals("doc"), "'doc' node expected: %s", docNode.getName());
          
          for (String fieldName : docNode.getMemberNames()) {
              UNode fieldValue = docNode.getMember(fieldName);
              parseFieldUpdate(fieldName, fieldValue);
          }
          return this;
      }
docs: Parse an object rooted at the given "doc" UNode. All values parsed are stored in
  the object. An exception is thrown if the node structure is incorrect or a field
  has an invalid value.
  
  @param docNode   Root node of a "doc" UNode structure.
  @return          This object.