code: func (mc MongoClient) ValueDescriptorByName(name string) (contract.ValueDescriptor, error) {
  	mvd, err := mc.getValueDescriptor(bson.M{"name": name})
  	if err != nil {
  		return contract.ValueDescriptor{}, err
  	}
  	return mvd.ToContract(), nil
  }
docs: // Return a value descriptor based on the name
  // Can return null if no value descriptor is found