code: func (g *Graph) Set(s string, val interface{}) *Graph {
  	if g == nil {
  		return nil
  	}
  
  	// Parse the input string into a Path graph.
  	path := NewPath(s)
  
  	if path == nil {
  		return nil
  	}
  	return g.set(path, val)
  }
docs: // Set sets the first occurrence of the given path to the value given.