code: func (g *Graph) GetString(path string) (string, error) {
  	// If path is "", return .String()
  	if len(path) == 0 {
  		return g.String(), nil
  	}
  	i := g.Get(path)
  	if i == nil {
  		return "", errors.New("not found")
  	}
  	if i.Len() == 0 {
  		return "", errors.New("Get() design error: not subnodes")
  	}
  	return _string(i.Out[0].This), nil
  }
docs: // GetString returns the result of applying a path to the given Graph.
  // The result is returned as a string.
  // If the error information is not used, then this method is equivalent
  // to Get(path).String()