code: func (g *Graph) addEqualNodes(g2 *Graph, key string, recurse bool) *Graph {
  	if g2 != nil {
  		for _, n := range g2.Out {
  			if key == _string(n.This) {
  				g.AddNodes(n)
  			}
  			if recurse {
  				g.addEqualNodes(n, key, true)
  			}
  		}
  	}
  	return g
  }
docs: // addEqualNodes adds subnodes of the given Graph to the current node,
  // if their content equals the given key. Optionally recurse into subnodes
  // of the receiver graph.